Transcript for:
Node.js and Express.js Fundamentals

this eight hour course will teach you the fundamentals of node.js and express so you can start creating backend and full stack web apps using javascript this course was created by john smilga john has created a bunch of courses including many of the more popular courses on the freecodecamp youtube channel john's teaching is very hands-on so you will create a bunch of projects while you're learning what's up everybody this is john from coding addict and welcome to node and express tutorial video where we'll cover fundamental building blocks of node and express js framework now since i want everyone to be on the same page we'll start the series with node and express fundamentals and gradually move to more complex topics we will build complex rest api with express.js as well as full-blown mern application in this comprehensive node.js course you'll not only learn fundamentals of node but also many related technologies like express.js framework mongodb as well as mongoose the main goal of the course is to show you how to build modern fast and scalable server-side web applications with node like in all my other courses to solidify our knowledge we'll build a bunch of cool apps and go through the steps of deployment as well lastly let me just say this if you're like me and you enjoy learning new tech by building projects instead of going through the slides you will enjoy this course all right and let's start by answering the most obvious question first what is node.js and even though there are plenty of good answers out there the one that i like the most is this one node.js is an environment to run javascript outside of the browser node.js was created in 2009 and it's built on top of chrome's v8 javascript engine as you probably are aware of every browser has an engine a tool that compiles our code down to machine code and chrome uses one by the name of v8 in extremely simple terms the creator of node ryan dahl ripped out the v8 engine and build node on top of it since the moment it was created node has evolved tremendously and while there are many things to like about node i particularly enjoy large community around node since that tremendously saves time on feature development as well as the fact that with the help of node it's never been easier to build full stack apps since both front end and backend are essentially built in the same language and you guessed it that language is our beloved javascript as far as course requirements go there are not that many my expectation is that you are familiar with basic html elements simple css rules and have general understanding of javascript especially es6 callbacks promises and a sync await since this is a node course and i already have tremendous amount of node content to cover i'm not going to spend too much time on javascript language fundamentals while you can still follow along with the course without knowing basics it's crucial if you want to understand how stuff works behind the scenes as a side note if you need to brush up on the javascript fundamentals i have a youtube channel called coding addict where i post a bunch of cool javascript related content specifically you might be interested in js nuggets playlist where i cover a bunch of useful es6 features as well as asynchronous javascript topics so if you need to jog your memory on javascript fundamentals i suggest going to youtube look for the channel by the name of coding addict and then more specifically the playlist by the name of javascript nuggets when it comes to course structure it goes something like this in first section we'll get familiar with node.js as well as my dev setup in the second section we're going to install node.js and quickly cover some general differences between browser.js and node.js then we'll spend some time on node.js fundamentals in section 3 and after that we'll learn what is express.js in section number four and once we're done with node and express fundamentals so once we're done with pleasantries then we're after the races where effectively in every section after that we will build a bunch of cool node.js apps all right and before we install node let's quickly cover some major differences between browser javascript and node.js so essentially how node.js apps are different from the browser javascript apps and let's start with the biggest one when working on node.js app you have no access let me repeat no access to browser apis since well they don't simply exist in node there is no browser so there's no dom there's no geo location no fetch and all the other cool browser goodies you see unlike browser apps that are interactive for example user clicks the button or toggles the nav and that sort of thing with node we build server side apps and i know it's hard to picture that right now but our node apps will only consist of pure logic without the graphical interface on that note you know how in browser apps we use a bunch of cool things available on the window object yeah sorry to break it to you but that's also not available in node so at no point in the course we'll write document.queryselector all right and once we have covered things that node.js does not have let's switch gears and see some of the goodies that node has to offer for example unlike browser we can access file system info about our operating system respond to network quests just to name a few also another major benefit of node is the fact that it's based on versions so unlike browser apps which depend on the user's browser our node app depends only on node.js version it was built in so in other words if we build a browser app and if our user's browser does not support a specific feature it is our responsibility to fix it otherwise our app might have bugs correct but when we're done building our node app there's no rule that we have to upgrade to a newer node.js version and possibly break our app we simply can keep running our node app in the version it was built in and without any worries go on about our day lastly unlike browsers where modules are optional in node.js you have access to modules by default and it's hard to imagine a node app where you're not going to use them as a quick side note under the hood nodejs uses common js library for the modules and while the general idea is exactly the same as for the es6 modules that we use in the browser syntax is a bit different as far as the install it's as straightforward as it gets just navigate to nodejs.org pick a lts version answer yes to all the questions and if you don't get some weird bugs congrats you have installed node in order to check if everything went correct just type node version in your terminal and you should see the version number if you don't you'll have to troubleshoot the error now as much as i would like to help when it comes to install it's impossible for me to troubleshoot your local setup so when it comes to troubleshooting install errors i strongly suggest using your favorite search engine instead typically within a matter of minutes you'll see a bunch of useful solutions to your exact problem lastly let's also talk about versions as you can see at the time of the recording i have two options 14 lts or 15 current one if you read the note docs you'll see that for production apps they always suggest using lts which stands for long term support and therefore i will also suggest the same but as far as tutorial i don't think you'll have any issues if you use the current version instead now also since you're watching this in the future your version number most likely is going to be greater than 14 basically greater than mine i definitely suggest installing the lts option that's offered to you instead of downgrading to my version and if you're stressing about content being out of date let me assure you that everything we cover in the course will work perfectly fine with your current note version and eventually if some bugs do creep in i will definitely update the course content so long story short just install your current lts version whatever it is and you'll be in good shape so in my case it is 14 i have two big buttons and of course since i would want to go with lts i'll click on left one then notice we are getting the download package and now i just need to go to my downloads and then crack it open and then like i said we just need to answer yes to all the questions so we go with continue continue and yep i would agree and again we just install and then we'll be prompted for our passport and once we add that one we should be in good shape and then like i said once the install is complete and yep we'll move this sucker to the trash then if we go to our terminal and if i massively zoom in and if i type node version there it is i should have my version number which in my case of course is 14. if you also can see the node version in your terminal you are in good shape and you can continue with the videos if not please troubleshoot it because otherwise everything we're about to do next is not going to work since you haven't installed node on your computer install is complete hopefully we all have node on our machines now what what do we do for contrast with vanilla.js it was somewhat easy right we create index.html jam our javascript code whichever way we prefer and browser does the rest it evaluates our javascript code but what about node how do we get node to evaluate our code and effectively we have two options a repl which stands for read eval print loop and cli executable which just means running our app code in node if i have to be perfectly honest reply is for playing around and cli is essentially for everything else in fact this is going to be the first and most likely the only time we'll use a rebel in this course and after that cli is going to be our best friend how do we spin up the rebel well we go to terminal and in terminal we simply type node and then no arguments nothing we just press return or enter however you would like to call the button and that's it now notice we have this little angle bracket that just means that we are in the rebel and once we are in a rebel we can do reply things what would be a first ripley thing we can do well we can simply type our name so cons and the name is equal to john and there it is of course now i can access name and my name is john as you can see you're not going to write anything serious in here and if you have written any vanilla javascript apps you know that of course we can also do the same thing in a browser console so we can also evaluate some code there but of course we're not going to write anything serious in a browser's console so the same thing is for reple yes we can come here we can play around but when it comes to serious applications of course you'll pick a cli executable instead and in order to close the repo we simply go with control and c and as you can see we have suggestion that we need to press it again and now of course we're out of the rebel not bad that bad we now know how the ripple works but what about a more serious node application how do we get node to evaluate our code well we would need to start by creating a project right so back on my desktop i'm going to create a new folder and surprise surprise i will call this tutorial why well because we'll do tutorial things and i'm going to say tutorial now of course if you want you can add node but i'm just going to leave it as a tutorial and then of course we'll have to use our text error in my case like i already previously mentioned i'm using visual studio code and my preferred method is just drag and drop and then instead of the folder what i would want is to create a new file and this is the case where you can literally name it whatever you would want and in my case i'm going to go with app and js and in this app.js okay now we want to write some more serious node program and the program is going to be following where there is a const so there's a variable by the name of amount and as a side note i'll make this bigger and i'll probably bump up the font size just so we can see a bit clearer so we're gonna go with const and not also close the sidebar hopefully you see that i have the file by the name of app.js and like i previously mentioned we're going to have a variable by the name of amount and it's going to be equal to 12 and now let's set up a if condition where if amount is less than 10 then we simply cancel log small number and otherwise we'll just say that the number e is large so we go with if and we're looking for amount is less than 10 and if that is the case we go with console log and we'll just say small number and otherwise if it is of course equal or bigger than 10 then we go with console log and we say large number and at the end of the day we just write console log hey it's my first note up as you can see an extremely complicated functionality and in this case i'm just going to set up the template strings so you understand that of course we can use them here as well i'll say hey it's my first node app and if you want of course you can jam the hello world there somewhere as well since that is the traditional approach with the first program and then in order to execute this code we effectively have two options i can navigate back to my terminal and i can zoom in like so and of course now i'm in a root so i would need to navigate to the desktop and probably the fastest way is just typing cd and drag and drop my folder here okay so now as you can see i'm in the tutorial and in order to execute my code i just need to type node and then app.js now keep in mind that technically i could have done that from the root we just need to provide the full path where i go to users blah blah blah and then tutorial and of course the file name is app.js and let me bump up the font size even more and the moment we run it check it out we have large number and hey it's my first note app now if you don't believe me we can go back and we for example can say that the number is nine and of course again we would need to run the code and we're gonna go with node and then app js beautiful we have small number and we still have our hey it's my first node up again the whole point of this line here is just to showcase that not only we can use quotation marks but also we can use the template string as well so that's one option but if you're familiar with vs code you know that it has this cool feature of integrated terminal where effectively we have our terminal but it is right away pointing to our folder so we don't need to do this whole dance where we navigate to the folder and then run the app we simply can open this up and the shortcut is control and tilde and also keep in mind that of course you can navigate through the tabs the problem is that i always forget where it is and effectively we need to go to view and then you're looking for this terminal command here as you can see this would be a shortcut and tilde and in here we have nice suggestion that we already located in tutorial folder and what do we need to do well again we just go with node app.js why well because that is my file name so for the remainder of the course i'll use the integrated terminal that comes with this code just understand that both of them effectively do the same thing and there it is now i run node app.js because that of course is the file name and i have small number and hey it's my first node app and that's how we can evaluate a more serious code using node as i note if at any point during the course you need to compare your code to mine just navigate to website johnsmilk.com and the website is johnsmega.com and then either in the project page or in the homepage you'll find node express tutorial project so in the homepage you'll find it in the latest project so just keep on scrolling but if it's not here it's definitely going to be in the projects page and you can even filter it in order to save some time so look for node in here like i said the project name is node express tutorial and not any of these links will get you to the repo and at this point you can either clone it 4k or just simply download and you're looking for this node tutorial and in here you'll find all the folders as well as the files now keep in mind that eventually when we start working on express we'll have to get this repo anyway because i'll use it for starters since i have prepared some assets for you some assets that we're going to use in our examples so this is really up to you if you want you can get it right now just keep in mind that you'll have to get it later anyway and once we have executed our first code in node let's quickly cover the concept of globals or global variables in node and the emphasis is on the word quickly yes there are more global variables available but the idea is not to spend half an hour in slide bill instead i would want to give you a general idea and as we progress with the course don't worry we will implement them and that way you can right away see them in action not just some random general description and before we continue let me just mention that throughout the tutorial the code from the previous video i'm going to save in a file so for example remember our first complex app with a mount and all that so what i did i created a file name by the one hyphen intro js and then i just copy and paste it this is what i'm gonna do throughout the no tutorial part of the course so that way you can always have access to the code and if you ever need to you can jog your memory now if you don't want to use my one if you're adding your own comments and all that i would also suggest doing that where essentially just create a file just dump it and then that way you are slowly progressing on the course and if you ever need to go back and refresh your memory you always have that option and keep in mind that if you would want to run this file you simply go with node and then whatever the file name right so in my case that would be one dash intro js again i'm going to keep on numbering them because i'm just annoying that way but you don't have to that is really up to you so back to the globals when we work in vanilla.js applications we know a very cool thing is the fact that we have access to the window object and the reason why it's so cool because in the window object we can get a bunch of useful things right so for example we can get a query selector so i can select a node i can get built-in fetch and hopefully you get the gist now i don't want to rain on your parade but you know there's no window why well because there's no browser so there's no window object so if you'll try to access window node will spit back the error and most likely your app will crash now there are some globals of course there is this concept of global variables and essentially what global variables means that anywhere in your application you can access them so no matter how complex my application gets how nested it gets or whatever i'll always have access to those variables and again let me repeat these are just some of the variables of course there's more and i'm not going to spend hours and hours talking about them i simply want to give you a general idea and then like i said we'll start using them and you'll see them in action and in my opinion that's just going to make it way clearer about what in fact they're doing and some of the useful ones we have their name so that would be underscore underscore their name just going to give us path to current directory then we have also underscore underscore filename which as you can see is going to give us a file name then we have require which is a function to use modules as well as the module that would be info about the current module now these two will literally cover them in the upcoming videos because our next big topic is going to be modules so for time being just remember that we have require and module and you'll see them in action in no time and then we have a very very very useful one and that one is a process and why it's so useful because it gives us a info about the environment where the program is executed because we need to keep in mind when it comes to a node app at the moment yeah we're executing that on our machines but when you deploy for example your api so for example your server right where is it sitting it is sitting on digital ocean or herald core or whatever so that of course is already a different environment and of course based on that environment you can make a bunch of decisions in your application again if you'll take a look at the process right now it's just going to be a giant object of gibberish data but trust me as we're progressing we the course will find a bunch of useful properties that we'll implement in our application now any of them you can simply console log and you'll get that useful data so you can just run console log and then for example their name again i'm not going to cancel log all of them probably the biggest one is going to be the process like i said you'll get a bunch of properties that at the moment will look like a gibberish and i simply need to save and of course then we go with node and app.js we run that and there it is now of course this gives me the path so if you're interested of course you can console log rest of them as well but in my case i'm going to stop with their name now also very quickly yes you have access to the console so as you can see in order to cancel log we have to use the console so that is also something that is available globally then just like in the event ljs we have set interval as well as set timeout so you can run these ones and i'm not going to run both of them but i'll show you set interval very quickly just so you don't think that i'm cheating and the way it's going to look like of course we have our callback function and then i'll say that my interval is going to run every second and i must type hello world otherwise well what kind of tutorial is this and again we simply go back to node and then app js and as you can see now after every second i have hello world in console and in order to stop it remember the command was ctrl and c and before we move on and start talking about the modules let me also mention something else where essentially we don't need to type node and then app.js you can simply write node and then app however throughout the course i'll probably keep on typing js just because i'm annoying that would be the first thing now the second thing and this is not a node thing this is actually a terminal if you don't want to type it you can simply go back to the previous command and in order to do that you need to press on arrow key up and check it out the moment you press notice that was my previous command and then i have one before that so in my case that is node and then app.js again you don't need to add that just extension but probably i will and then you just go back to the previous command and then press and again you just execute that command and of course if you want to clear the console again this is not a node thing this is a terminal i just type clear and lastly to answer the question that's probably bugging you the most we always have to just type node and then the file name because as we're going to be testing a special in tutorial it will probably get annoying and the answer is yes but only for now once we learn about npm the external packages which at the moment i fully understand doesn't make any sense at all then there's command that effectively will restart our application so we'll have to install some third-party module some external library and that will do the job of restarting the application for now yes all throughout tutorial up until the point where we cover that external library and external libraries in general yes we'll have to type node and then whatever is the file i know it's a little bit annoying but i just don't want to skip ahead i want to get us there with a full information of what is happening so with this in place with clear understanding of the global variables in node now let's move on to our next topic which is going to be modules in node beautiful and once we understand the globals in node now let's talk about the modules and first let's return to this command notice we have here node and then app.js probably the question that you have is well does that mean that all my application needs to be in this one file and the answer again is yes and no yes you'll execute one file but you'll split your code in modules otherwise that would be literally insane to jam all your code in one file and effectively i'll just show you with an extremely complex app and of course extremely complex is in the air quotes right now and you'll see why we'd want to use the modules in the first place so in the next video i'll give you official intro with a bunch of gibberish and all that but for time being let's just build super complex app and then see why i would want to use those modules in the first place and if you have any familiarity with es6 modules if you have worked with them in vanilla.js or in react.js you're already in good shape the syntax is going to be tiny bit different because you know it uses common js but the general idea is exactly the same and we start with a simple function by the name of say hi you guessed it and then this function is going to be looking for the name parameter and then inside of the function what do we do we simply cancel log and we say hello there and then whatever is the name of the dude or the gal that is being passed in as a parameter and of course we can invoke it and i can say say hi and then pass in susan for example and in order to make this interesting i'll set up some variables as well so i'm going to say const john is equal to john and you guessed it since there's a john there also has to be a peter and hopefully you get the gist so imagine we would have a bunch of names and then we have probably more functions than this one but for time being this is just going to be say hi we copy and paste we invoke this function i guess three times one for johnny boy one poor peter and then the first one we already have for susan and what do we do we run node app or app.js we run that and there it is now of course in our concert we can clearly see hello there susan blah blah blah now wouldn't it make sense if the names would be separate as well as this function or the future functions that we're going to create would be in separate files and then we can access them all throughout the application and that way of course we would have smaller files and more structure to our application and that is exactly what the modules allow us to do and that's why we'll move on and start talking about the modules in the next video beautiful and once we understand the main problem with this code where again the moment code is technically still tiny but as you can see it is getting bigger and more annoying with every line now let's talk about the modules and i guess let me just give you the main idea first and then we'll talk about the implementations and all that good stuff so first of all what are the modules again if you're familiar with es6 modules you already have the idea but essentially that is encapsulated code and the key here is that we're only sharing what we want so we're only sharing minimum how would that look like in real life well i can go here with secret and then i can type here super secret and then since this variable is in this file as we can see you can access anywhere okay so by mistake i can just access it i can override it now of course you can make an argument that i mean it is made with cons but hopefully you get the gist this is available to me everywhere in this file so once we set up the module you'll see what are the differences now node uses common js library under the hood that's what makes it happen and then every file in node is a module again let me repeat every file in node is a module so those super powers that we will cover in just a few seconds we have them by default we don't need to do anything we don't need to go to the store and buy some javascript code no we just get them by default and the way the modules work well we simply need to create a new file right and i'll right away set up the names here because of course eventually this code will be sitting in the file name by the three hyphen and then the module basics or whatever but the names as well as the function well it's going to be in a separate file so what i'm trying to say is that in a root of course there's no folders or nothing so everything is rude i'm going to go with four again i'm doing that because eventually this is going to be three hyphen modules something i'm gonna go with maybe names or you can type first module whatever you would want and i'm just gonna go with names.js okay awesome and then i'll take these three variables from my app.js and i'll copy and paste in the names and then also what i would want is to set up one more file and of course this one will be five and i don't know we can say second module or so i'll say here utils something generic so we set that up and now of course what i would want is to grab this function from the mgs and copy and paste in the utils and now sixty four thousand dollar question is this app gonna work or is it gonna break and of course the answer is it's gonna break because we have no access right now to say hi or to john or peter so why don't we go to the names and console log something and as i said yes you can console log this in the app.js it is a file so by default it is a module but since we'll do most of our work in the names and new tools first why don't we go to names and that way we can also see how we can run the file just by using node and what i would want to console log is the global by the name of module so in the names go below or above the variables doesn't really matter and go with console.log and then module and remember to run node and then whatever is the file name so in my case it is four dash and then names js you run this and you'll notice something pretty pretty cool where we have the object and in that object we have quite a few properties now the one that i'm interested in the most is this exports one and it tells me that this export is an object and the way the common js syntax works whatever i'm going to dump in that export i'm going to be able to access anywhere in the application so that's the key remember we're only sharing the minimum so it's up to us to set those values in that export object we decide what goes in there previously remember secret was accessible everywhere in my app.js now in the names i can be hey you know what john and peter yeah i'm sharing them anywhere in application we can access that but the secret variable no this is just going to be local so i'm going to add here i guess the comment by the name of local and that way at least we understand so this is going to be i mean i'm not going to use global but i'm just going to say that share so we're sharing this with rest of our application and then if i know that this is a object and it is sitting in the module how does that work well we go with module then it is an object so we go with export and we have multiple ways how we can set this up but the most basic one will simply say that yep it is an object and inside of that object there's going to be two properties john and peter now i can probably already guess that we're using a es6 syntax since the key name is exactly the same as the value well we can simply pass it right so we have john and peter so now what happens in the app.js we can access them so i can go back and this is the case where we'll need to run that require remember in the globals we talked about this function so in order to share them we need to use module.exports and essentially i'm setting up the object like so where i go with whatever values i would like to share now in order to access them i need to go with require and i can assign it to a variable or i can simply require now in our case we will assign it to the variable and i'll use the same type of syntax where i'm going to go with names just so we can console.log that and this is going to be equal to require so that's my function and as a parameter we need to pass in where the module is located so where is this data coming from and always always always always you will be setting up your module you have to start with dot now sometimes your modules will be two levels up i don't know three levels up whatever then of course you'll start with dot dot but you'll always start with this one dot because there's also going to be a third party modules and there's going to be built-in modules in node and then we'll use just these quotation marks again super super important every time you create your own module you'll have to start with dot and then forward slash so essentially you're giving a path now in our case what is the path well i'm looking for the names right so i set up here the path and then if i cancel out the names i should see something pretty pretty cool where i go with names and there it is now i'm going to run node and then app js now keep in mind we're not running names anymore we go with node and app.js now of course still complains that we have no access to hi let me comment this one out so let's say node and app.js and check it out now of course we have the object with john john and peter and peter and we explicitly said what we would want to export so we go with exports and that way no one has access to the secret one so this secret one is only for this file and of course we can do the same thing in the utils as well right so we have the say hi and we go with module and export and i can just simply set it equal to now the reason why i was setting this up as a object because i had multiple things at john and peter and don't worry in the next video i'll show you alternative syntax how you can also set this up but in this case i have object and then of course i'm setting these properties and i said note this is just my preferred way of actually using the exports again there's multiple ways how we can do that and i will cover the other ways in next video but this is just my preferred method that's why i right away set my exports equal to an object and then pass these two properties and in utils since i only have one thing i'm just gonna go with say hi that's it i'm saying that i'm gonna be exporting my function so say say hi like so and once i have exported my function now of course i need to go back to the app.js import my function the same name and i'm going to go with say say hi and that one is going to be coming from the different file of course so we go with five and then utils and notice here how we don't need to pass in the js if it is ajs file we just simply omit the extension as long as the file name of course matches and then i can remove now if you want you can cancel log but i already know that i'm gonna have the function over there i'll uncomment my say hi so now of course there's going to be no error and let's make a clear console and again we run the node and then app js and there it is now of course we have a different error where it says well john is not defined all right but i know that john is sitting in the names right so here we have multiple flavors either you can destructure it so instead of going with names i can go john and peter that is definitely one option or i can go with property names right so i can say names and then john and then the second one is names and peter names and peter and now hopefully everything works otherwise you're probably thinking that i'm just messing with you there it is now we have hello there susan john and peter and effectively what we did we separated our concerns again the main idea is that every file by default is a module and then when it comes to a modules we are in charge what we are sharing and in order to export or make it something available from this module we go with module exports and then we just set up the functionality whether this is going to be a object that we're exporting or we're simply exporting as a function so we set this equal to to the exports and if you're familiar with es6 modules as you can see this is very familiar to the export default and then whatever you're exporting as default whether that is a function whether that is a react component or whatever notice i'm exporting as default so of course when i'm importing this in this case app.js well i already know that this is a function so i can name this whatever i would want and the same goes here since i'm exporting this as object i can call this shaken bait as long as i access it later of course i'll be able to access the property as long as the name matches to whatever i set up over here so let me save this and now of course we can talk about our next topic all right so far we know two flavors one if we want to export one value we just set module export equal to that value and then of course wherever we want to use it we just import it set it equal to some kind of variable and of course once we use that variable we have access to that value and the second flavor is if we have multiple values then we simply set module exports equal to an object and then in that object we set up the properties however there's also another way how we can do that and essentially it is called export as you go and the way it looks like first i'm gonna set up a new file and i'll call this six and i'll call this alternative flavor now again naming is really up to you since that is the hardest thing in programming and then i'm going to come up with one array and i'm going to call this items and that will be equal to item one and item number two and then i'll set up a object and i'll say const person is equal to a object and there surprise surprise we'll go with name property and set it equal to bob and i'm purposely adding multiple data types just so you don't think that we can only export variables or functions and in here we have two options either where we are setting up the value in this case items i simply go with module exports and then whatever is the name and of course in this case i'm going to keep the items but notice the syntax where instead of going with const items i right away go with module.exports or if you are a true rebel you can do something like this module exports set up the property for example single person and set it equal to your person object why we are able to do that because if you remember in the previous video when we console logged module exports it was an object right so what are we doing here we're setting up a property on that object and set it equal to an array and here i set up another property and just set it equal to a person keep in mind of course i can still write simply module exports and then the person but since you might sometimes see this type of syntax as well i wanted to cover that and now of course we save alternative flavor.js and you're probably not going to be surprised that if we navigate to app.js and in this case i will call this data because i'm getting a object and on that object i have two properties and i need to come up with some kind of name now as always this name is really up to you you can call it shake and bake you can call it uncle bobby whatever you want in my case i'm gonna go with generic data we go with require again we're looking for the file by the name of alternative flavor and in this case i'm not gonna do anything with it apart from console logging and if i navigate back to my integrated terminal and run the node app.js there it is of course now i have the items as well as the single person now please keep in mind one thing where this syntax whether the first line or line number six at the end of the day is exactly the same like we're doing over here yes the syntax is a bit different but at the end of the day you just make these values available somewhere else in your code now just because i prefer this type of syntax most likely throughout the course you'll see this approach but if you prefer this one instead be my guest at the end of the day it is your application and you are the one who is going to be maintaining it and before we move on to built in modules as well as third-party modules let me throw you a mind grenade and i'm going to start by removing this console log in the app js like so and i'm going to create a new file with the same exact name a mine grenade as always if you would like to call this differently that's totally your option and i'm going to go with mine grenade like so and js and in this file i'll create some basic functionality and by the way let me save app.js so let's go with const num1 is equal to 5 and then const num 2 is equal to 10. of course there has to be a function that adds these values as always with every tutorial so go with add values just for the sake of it i'm just going to go with good old function keyword and the old setup meaning not the arrow function syntax and simply here we'll go with template string the sum is colon and then of course let's go for template literal and we'll say num1 plus num2 and instead of setting up the exports i'll simply invoke add values and now i'll throw you that migrate that i was talking about where in the app.js i'm not going to assign it to anything i'll simply write require and then we'll go with my grenade and now let me comment out these three since at the moment they will just over populate the console and again let's run node and app.js and once we're on our code we can clearly see in the console something pretty interesting where we have a log of the sum is 15. so what's happening over here well when we are setting up everything if we have a function inside of the module that we invoke yes that code will run even though we didn't assign it to a variable as you can see clearly here and we didn't invoke that variable and before we go any further let me mention three things first it's not unique you can also do that in es6 modules and if you took my vanilla javascript course you know that we use that functionality number two yes throughout the course here and there we will use this particular setup now it's going to be with third party modules and of course once we get there i will remind you about this setup so that's how it works and third i wouldn't suggest losing your sleep over it just please remember that when you import a module you actually invoke it and this is really going into weeds but the reason why that happens is because this code is not just exported on its own when the node exports this it actually wraps it in the function so that's why when you're required yeah you do invoke the code if you have some kind of function that actually is executed here keep that in mind not talking about exporting something i'm talking about executing function here and there and of course in this case you need to use the imagination that we'll do something way more useful than this at this point you're looking at it okay i could have just set up that function in app.js and you're 100 correct this is the place where you definitely need to use your imagination where of course the functionality we'll use it for is going to be way more complex but the idea is going to be similar where we'll just require some kind of module and behind the scenes that module will do a bunch of cool stuff okay that was fun we created our first module and in the process covered the general module syntax and use cases as well now what well as helpful as our say hi function is some very smart people created way more useful modules than that and the good news is that we can start using them right away so what i'm trying to say here is that node has bunch of built-in modules that we can use freely in our apps in the following videos we're going to cover following modules os module so operating system module path module file system module as well as http module to set up our http server and before we continue let me just say this i purposely cover only a few major modules and more specifically only a few properties and methods provided by those modules you see the list of built-in modules in node is quite big and the amount of properties and methods each module has combined is of course even bigger and as a result we could easily spend the remainder of the course on just that but is that really beneficial and of course the answer is no instead let's cover the general setup first and later as we progress with the course implement some modules as we go now if you're interested in more properties and methods built and modules have just navigate to the docs and go nuts so if at any point you would want to find out more about specific property or method or the built-in module in general just navigate to nodejs.org and then look for the docs and again in my case the version the long term support version is 14 so i'm gonna click here but as you can see we also have an option of going to the older versions as well so as you can see i can get the docs for the older versions as well but i'm just going to stick with my version and then be prepared to go nuts if you enjoy docs then you have yourself a big old party where of course you can look for modules and then each module has the properties as well as the methods so of course you can get a extremely detailed information on the properties as well as the methods here in the docs all right and once we have covered the general existence of built-in modules now let's take a look at few of them and i'm going to start by creating that file that i promised a few videos ago remember when i was setting up the modules i said that eventually there is going to be a file by the name of 3n modules and this one i would want to do it together just so you don't think that i'm not fulfilling my promises so we're going to go with module and then i guess modules.js i'll grab that i currently have in the address it's pretty much everything and we copy and paste and in this case i also uncommented these say hi again this all stays for your reference and you'll have access to it if you navigate to the github repo so grab everything in app.js i'll actually cut it out since we'll start from scratch and copy and paste now of course all this code is sitting in the modules and just keep in mind that of course we're still referencing the names utils alternative flavor as well as my favorite the mind grenade and back in app.js now let's start by taking a look at the os module and os module we built in module provides many useful properties and methods for interacting with operating system as well as the server and the general setup for the built-in modules or even the external ones that we're going to cover a bit later is going to be similar where we're going to go with some kind of variable and in this case i'm going to call this os for operating system then we're going to go with require and then in the require we'll have to pass in the name so since this is a built-in module of course we don't need to install anything just remember it later when we work with external ones yes we'll have to install that module first in this case it is a built-in so we just go with os but again let me stress something we're not doing dot and then forward slash no we just go with os so that way node knows all right so you're looking for the built-in module and once we set this up then we have multiple options either you can access those methods by just running this variable so it would look something like this where i go with os and notice the moment i press dot i have all these options so these are the methods and properties that i can use or if we know that we want a specific one you can simply destructure it here and of course throughout the course i'll use multiple setups just so you understand that both of them effectively do the same thing so here i have access to all the methods and properties that this module provides and of course now we can go crazy for example i could get a useful info about the current user which of course is me so say info about current and user and you know what as a side note i'll save here and i'll close all the files it's just a bit annoying that i have all those tabs open back in the app.js once i have a comment of course now i would want to assign it to a user and we'll simply go with os since that is the name of my variable and then method that i'm looking for is userinfo i don't need to pass anything i simply invoke it and of course since i would want to see the result i simply go to console log and then i'm looking for the user and you can probably already guess that we'll just run node app.js and there it is now of course i have a info about the user which is me so this would be a home directory this is going to be the default shell and all kinds of useful stuff then i want to show you how we can get the uptime of the system so effectively how long the computer has been running in seconds and i'll just add a comment method returns the system system up time up time in seconds and the way i'm going to run that i'll right away set up the console log just so you understand that of course we have multiple options how we can invoke those methods you don't always have to assign to some kind of variable now i'll leave this one in here so i'll leave the console log and then user and let's say right above or you know what let's do it this way so leave the console log where the user is and then let's go with another one we'll go with console.log in this case i'm going to go with template string and we'll say the system system uptime yes and then let's use a interpolation of course and the method that i'm looking for is uptime so again i go with my variable name and i know i've said this before but i just want to stress this point just so we all are on the same page and in this case i'm going to go with os and then the method name is uptime and then let's just add seconds and again same deal back in the integrated terminal run node and then app.js and there it is now of course not only i have the info i also have the system uptime and what's interesting this actually is 100 seconds meaning if i'll run this notice that you'd expect that this would probably stop at 60 right since we have 60 seconds in a minute but no actually this one goes to a hundred and then i'm just gonna set up a object where i'll show you a few more methods and then we'll move on to a next module because again the point is not to cover each and every method the point is just to give you a general idea how the modules the built-in modules would work in node so clear my terminal and then i'll create a object i'll call this current and then os and then in this object i'll set up properties and i'll set them equal to the method that actually returns that value from my os module so go with name and os and this is going to be equal to a type method then i can get the release and this one will be equal to os and then release again we invoke it then we'll look for total memory and free memory total and mem and of course i'll go with os and then total mam as you can see somewhat predictable and then we're gonna go with free memory and it's not going to be surprised if we're just going to go with free memory here let's save that one and lastly let's just cancel log it and we should get a bunch of info about our current operating system again we're going to go with node and then app.js and not only have the user information not only i know how long the system has been up in seconds i can also get some useful data about my operating system and again we're just scratching the surface of course there's more methods and properties but hopefully you have a clear understanding how powerful these built-in modules are in node.js since the node we can interact with the file system something we couldn't do when we used our javascript in a browser another useful module is a path module which allows us to interact with file paths easily and i'm going to remove all my code in the app.js because behind the scenes i created a file by the name of 8 os and module and of course copy and pasted the contents from the previous video that's why in app.js i'll remove everything and the setup is going to be exactly the same we come up with some kind of name now most likely it's going to be path and then we pass in the module we would want to get and in this case of course it is a path module and then let's just start with a very useful property a separator property that returns a platform specific separator so if i go straight up with console.log and then path sep this is going to return my platform specific separator so if i write node mjs there it is and of course i have forward slash now if you're using different platform for you the value might be different after that let's take a look at the path dot join so the join method which joins a sequence of path segments using that platform specific separator as the limiter and second thing it does it returns a normalized resulting path and in order to show you an example i'll create a new folder so not a new file but a new folder i'll zoom in and i'll say content and inside of this content folder i'll create another one and i'll simply call this generic subfolder and in this subfolder i'll say a test and text file and instead of the text file i mean you can place something you can omit it doesn't really matter i'll just say text and then txt and once we save it back in the app js now i want to use that path dot join method so i'll say const and then file path is equal to path dot join and then we need to pass in those values as strings so for example since i'm looking for the content folder i'll simply say forward slash and then content then i know that inside of the content folder i have the subfolder that's another folder and then eventually there's going to be a test txt so we go with test and then dot txt we save the sucker and then if we'll cancel log the file path we should see the whole path and there it is now of course it is normalized and we get it as a value so we have content subfolder test and txt so if i start adding some type of forward slashes meaning trailing slashes then of course they will be removed we still get the normalized path and we can also get the base name so for example i create this file path but i only would want the last portion of it how can i access it well the method name is base name so we're gonna go with const and base and path dot base name and we just pass in that file path and now if we cancel log the base we should see the text again these are just summaries if you want just a directory of course you can imagine that there is a method that returns that as well but since i don't want to cover each and every method that's why i will skip that one and there it is now of course not only i see my normalized path but i also see the test txt which is my base and the last method that i would want to showcase is path.resolve and why it's so cool because it returns an absolute path and once in a while in our applications we need to provide that absolute path that's why of course we'll have to use that method and when it comes to path.resolve it accepts a sequence of paths or path segments and resolves it into an absolute path so below the base i'm going to go with cons and then absolute and that one is equal to path and we're looking for dot resolve and here remember when we talked about the globals one of the first globals i covered was underscore underscored their name so this is going to point to this directory where the app.js is located and once we're here then of course we just need to provide rest of the values in my case that is content then i'm looking for sub folder and then eventually i would want to get to the test dxd i would want to get this absolute path and then once i set up the value of course if i go with my console.log and if i provide absolute once i run node and objects you can probably guess that in the console i'll have my absolute path to the test txt and if you're wondering why we would ever want that well remember our application is going to run in different environments right so of course the path to some kind of resource is going to be different in my computer in my local machine than for example in heroku hopefully it is clear and now of course we can take a look at the next useful built-in module nice now we know how we can work with path module and like i mentioned in the previous video we also have an option of interacting with a file system so what i would want right now is first create a new file i'll call this nine and we'll say path and module like so js i'll grab everything that i have in the address copy and paste and once we have this one out of the way i'll just remove and keep the app.js clean for now as well as clear the console and yes we have an option of interacting with the file system and the module the name of the module is fs now essentially there are two flavors when it comes to file module we can do it asynchronously non-blocking or we can do it synchronously which is going to be blocking but for time being we'll just cover both of the setups and then later in the course we'll cover what are the differences and why you should prefer one over the other one for now just think of them as different methods but eventually yes we'll talk about it the whole structure of the node and why would you want to use the non-blocking code instead as well as different approaches when it comes to callback functions different solutions and for now i just want to show you both methods essentially four methods and then we'll just move on to the next topic and in order to set this up in this case i'm just going to structure right away the methods that i'm looking for and in the first video we'll take a look at the synchronous ones so that's why i'll destructure read file and sync and that is coming from require and then the module name is fs again please keep in mind it would be the same thing if i were to go like this fs and then fs and whatever the name i was going with read file sync and of course i have access to it i'm just showing you a different way how we can access those methods we just destructure them out of the fs module and then the second one will be write file sync write file sync and then once i have the structured both of them then i'm going to set up two variables so first we'll read two files we haven't created those files yet but in a second we will and then eventually we'll create a new file with write file sync so i would want you to go to the content folder if you haven't created then i suggest creating one and i mean i'll keep the subfolder just because i believe the path module is still using it but in a content i'll create a new file so not in the subfolder but actually in the content i'll say first first and then txt so this by the way sets it up in the content so let me move it up or i'm sorry this sets it up in a subfolder i believe and it tells me do i want to move yes i would like to move and now i have the content that has the first txt and then i have the subfolder with test.dxt of course if you want you can place it in a subfolder that's really up to you but in my case i would want them simply in a content so i'll go the second one txt and as far as the values i'll say hello this is first first text file and then of course we can copy and paste the value and just change it around to the second file so in the second txt we'll say second text file and once we have both of the text files now let's take a look at how we can read from the file system and since we have read file sync we know it is a method and in that method we need to provide two parameters we need to provide a path to that specific file as well as well what is the encoding so the node knows how to decode the file and generally you'll go with utf-8 and we'll first go with first that's my variable we'll go with read file sync my method name and like i said we provide a path we go to the content and then inside of the content there's going to be a first txt and then as far as the encoding the default one will be utf-8 but if you want to be a bit specific just set up the second parameter and notice these are all your options and just go with ut effect okay and then once we have everything in place of course we can copy and paste this is going to be the value for the second one and we just need to change the file name of course so we have the second one and now in a console log we should see both of the text so if i go with console.log first and then second i should have one long text and let's go with node and app.js and there it is i have hello this is a first text file and i also have hello this is the second text file and once i have both of them why don't we create a new file and the method for that is write file sync and the way it works again we provide two values two arguments one is gonna be the file name and if the file is not there then of course node will create that file and you'll see that in a second and the second one is the value that we would want to pass and i'm going to go with write file sync write file sync and like i said first is going to be a path so you can call this third you can call this result whatever you would want in my case i'm going to go with forward slash content and then we're looking for result and then sync and this is going to be txt and then as far as the value if you want you can simply pass hello world and test it in my case i'm going to make it a bit more interesting where we'll set up a template string we'll say here is the result and why don't we use the interpolation we'll say first and second so we'll have first value and then the second value and you know what when we add here colon as well so let's say first and then let's place a comma and then we're gonna go with second again if the file is not there then of course node will create one and if the file is already there node by default will overwrite all the values that are in the file and i'll show you that in a second so i'm going to go here with node and app.js and check it out now i have result sync txt and then inside there i have here is the result hello this is first text file and also have hello this is second text file and just to showcase that if there are some values they will be overwritten by node well if i go with simple hello world and then i run node.js again i have my new result now if you just want to upend to the file well we need to pass in one more argument notice i have the first one i have the value that i would like to set up in a file and the third one is an object basically an options object and here the property name is flag and if you'll set this flag equal to a then node will append this and the easiest way for me to show you that is run node.js and now we should have two results so we have here is the result and notice how we're starting a new line why well because by default we are overriding everything and then when we add that flag then of course we create a new value so these are two very useful methods that we can use with node to read files as well as create ones from the scratch beautiful and once we have looked at the synchronous approach like promised i also would want to show you the asynchronous and as always let's start by creating a new file again in my case that is going to be 10 hyphen and then i'm going to go with fa sync and js and of course i'll grab everything in the app.js and then just copy and paste and then back in the app.js i would want to change these names so i'm not looking anymore for the read file sync i'm actually looking for a method by the name of read file so this is going to be the asynchronous one and the same goes with writefile now of course we can remove all this code as well and the way the synchronous method works we need to provide a callback and if you're familiar with callback essentially what it means is that we run that callback when we're done so when whatever functionality we're doing is complete then we run that callback just like we normally would do with add event listener on a button remember we go with add event listener we add whatever the event of course with the button that would be a click event and then pass in the callback function and that callback function will run every time we click on a button so this is the same thing where we have the read file function and we can simply use it since of course we have the structured then we need to provide a path so again we go with forward slash content and then the file name is first txt and this is where we provide that second argument and that is going to be a callback mission now in that callback function we pass into more arguments first one is going to be error if there is one as well as the result and then inside of the body first i would want to check if there is an error and then i can just return null as well as maybe console.log so we go with if error and then we'll say return null or simply return whatever you'd want and if you want you of course can cancel log the error as well like so and then if everything is correct well then of course i'll have access to my data which of course has the name the parameter name of result and since i would simply want to console log the result i'm going to go with console.log and the result but of course keep in mind that this is where you would set up the functionality so let's go back and we're going to go with node app.js and in this case something really interesting where we don't get the text right so we're getting this buffer so this is what's going to happen where if we don't provide that utf coding then of course we'll get the buffer now where do we add this encoding value well right here in between in between the content as well as the path so let's just go with string and we're looking for the utf so let's say utf-8 and we'll save that one and let's run it one more time and of course i have node app.js and then hello this is the first text file and now the million dollar question well how we can set up the same functionality check it out we have read file read file and then we simply create a new file with both of these values so if you're familiar with callbacks you know that of course we would need to set up that functionality inside of this callback where i'm getting this result otherwise there's going to be an error because the only way for me to access this result if i'm setting this as a callback is of course inside of this function and this is what i was saying before where yes eventually i'll show you a different approach because inevitably we'll set up a callback help and you'll see that in a second so what i would want to do right now when i get back my first text file well now of course i would want to assign it to some kind of variable and then i would want to read that second file right and then eventually once i read the second file then of course i would want to create that new file and the way it's going to look like i'm going to go with const and i'll say first and you can name it first text i'm just going to know it first and this will be equal to my result okay awesome and then right after that result again i'm going to go with read file and then the same thing we provide a path so we go with content and then in this case of course we're looking for second and then txt then we need to provide the encoding so node knows how to decode that and we go with utf-8 and then of course we need to provide our callback again same deal we go with error and result and in order to speed this up i will copy and paste so just grab everything starting with if and ending with the result copy and paste again this is the case where we're checking for the error first if there is an error we cancel log it and if everything is successful we assign this one to the second one and then eventually now i would want to set up my right file so again it is a function we need to provide that value and we already have result sync txt that's why i'll create a new one and i'll call this result and async so again we're looking for the content then we go with the filename which is going to be result and a sync and txt of course since there is no file node will create that for us i'll right away set up my data now if you want of course you can copy and paste this functionality this is totally up to you where basically we use two of them and in my case this is exactly what i'm going to do in order to speed this up if you want to create something from scratch of course that is also an option and i'm just going to copy and paste that's my template string and again if you want to add this flag you can definitely do so in my case i'm just going to omit that so here's the result i have first and second and the reason why i have access to them because of course i'm looking in the outside scope of this callback function and then again we have a callback function in the right file i know there's tons of callback functions that's why we'll have to set up a better setup when we're handling these callbacks but we'll do that a little bit later so for now let's just add a comment here where we have first parameter second parameter and then third parameter and of course this is going to be again our callback where we have error and result and then inside of this callback finally we can take a look at the value and of course the value will be in this result now of course we're creating the file and all that but hopefully you get the gist that if you'd be doing something where you're looking for this result of course it would be over here so again let's check for error quickly if there is an error then of course i would want to return as well as console log the error just in case and if everything is correct let me just console log the result so save it here and two things we need to watch out for maybe there's an error and second one we should create a new file by the name result and then async txt let me clear the console and we're going to run node app.js and i do get an error and error simply tells me that i did not add the dot in front of the content so i would need to go back to write file and just add that and once we add the dot we are going to be in good place where i'll clear the console and i'll run one more time node app.js and then the result will be undefined okay that's fine like i said in this case we're not expecting anything back but what's really cool that in the result async we should have our text here is the result hello this is first text and then the second text so hopefully it is clear this is how we would use the async pattern so let me zoom out right now here and you'll see this famous callback hell and in the next video i would want to give you a brief description of what are the differences between the asynchronous approach or non-blocking approach and the blocking one the synchronous one as well as what are the alternatives to this callback l all right and just to give you an early taste of the differences between the asynchronous or non-blocking and synchronous which is a blocking code why don't we set up few console logs now before we do that i will create a new file and i'll say 11 here and by the way i definitely need to zoom in just so you don't think that i'm cheating fs and async js and let's go to the address we'll select everything and copy and paste and of course in next video we'll set up different module in this appdress so for time being i can just remove it and then like i promised we'll set up some console logs so why don't we go back to fs and by the way during this video i'll zoom out because i definitely wanna go back to this evil evil callback hell that we're getting from nesting callback within the callback and as far as fa sync let me zoom in and why don't we set up a console log in few places let's say before we're accessing the file so i'm gonna go with log and we'll say start then we're gonna go with write file sync and then right after that we're gonna say i'm done with the task and then inside there let's write done with this task copy and paste and we're gonna go with starting the next one starting the next one meaning the next task so that should do it and of course i need to go with clear so clear my console and i'm gonna go to node and then the file name is 10 iphone and then fs and we're looking for sync i run it and notice something interesting where i have the start so that is going to be before i read the files and only then once i'm done writing that file i have done with this task and starting a next one and what we need to imagine that of course this task of getting those files as well as the second one of setting up that file well it might be very time consuming right and imagine that if we have even 10 users and they're all the time using our application and if for example this one user does this one task or both of them and they take really long time what means that node is not going to be able to serve other users and trust me it is at the end of the really really big deal and notice how javascript is reading this code synchronously it just goes line by line so we start with this task then we read these files and then we write the result and again if this is something that takes really long time then pretty much your application is down so no other user can do anything with that application because one of the users is for example reading these two files and then writing one again this is a very simple example but you need to picture that of course there's going to be tasks that take longer time and as an alternative let's take a look at the async approach so here again we'll set up some simple console logs and again we'll cover this in a bigger detail a bit later for time being let's just set up console logs and you'll see the biggest difference where i'm gonna go with log and let's say start so i'm gonna do that before i read this file and then i would want to go inside of the right file the last one and instead of console logging result which of course is undefined since in this case we are not getting anything back now i want to go with done with this task and then right after my first read file i'm going to go with log and starting next task hopefully you're able to follow along again before the read file inside of the right file and then right after the first read file because of course the other ones are nested inside of this callback and then if we go to node and if we just change it around to 11 and then fa and i believe it was async and if we run it notice something cool where i have my start and then i right away have this starting next task and eventually i have this done with this task so what this means is that since we have this asynchronous approach the moment we start this task we just offload we just offload this task and we continue with our code so that way when user number one for example comes here and wants to get this functionality yeah sure here node just offload this task and then your application can keep on serving other users again it seems a bit trivial at the moment because we have a basic approach but hopefully you get an idea where in one case we have everything happening line by line so only when we're done with the task we're starting a next one and with this approach we start a task and we just offload that task and then we start a next task right away and eventually yes we have done with this task in the console as well now as far as the implementation as far as the callbacks yes this is a bit messy right notice how we only want to accomplish few tasks and it's already somewhat off a pain now alternatives are using promises as well as async await now again hopefully you understand that when we talk about reading the file as well as the writing or file i use this as an example of some kind of task that would take a long time now for the remainder of the course mostly it's going to be reading from the database writing to the database and that sort of thing but this is a very good illustration of how some tasks would take some time so of course we would need to use a callback and as far as the callbacks yes you can use them but the code is going to get messy somewhat quickly that's why a bit later in the course we'll take a look at the alternatives which are promises and a sync await and i have to tell you honestly for the remainder of the course we'll use async await because in my opinion it is just easier to work with excellent and up next we have http module but before we continue let me just mention that i purposely won't spend too much time on explaining every single http method we're going to use in great detail and here's why you see starting from next section all of our work meaning code in some shape or form will revolve around server setup aka http module so that point of course i will cover every last bit of syntax in great detail at this point though i think it's just a waste of our time so if you're confused about something http related don't sweat it we will return to that subject shortly and cover it in far greater detail now if you're wondering why we bother with http module at this point at all since we're going to use it later anyway you see with the help of http module i believe i can show you some core features of node in action and give you somewhat of a visual representation of them otherwise i would have to base everything on slides and i don't think it's the best approach so long story short if you're iffy about something http related just please be patient and i'll answer all your questions in the next course section nice i think we've got a good initial understanding of how the file system module works in node and hopefully i did not lose too many of you so hopefully there are still some students left in the course because i fully understand that seeing this for the first time is probably a bit overwhelming and what i would want to do next is cover the last initial module the built-in module and that is going to be the http module which is going to allow us to set up a web server now please keep in mind one thing we'll just cover the basics because the large part of this course is going to be creating your own server and setting up the api now granted we will use an abstraction on top of the http module and that is going to be the package by the name of express but the whole point is going to be exactly the same that's why again we're not going to cover everything in greatest detail at the moment because i don't see the point of repeating myself and now i want to go back to objects i'll zoom back in just so you can see better what is happening by the way let me check my zoom level so i'm going with settings and i think that should do it my zoom level is two at the moment and then back in the app.js let's grab the http module and we'll assign it to some kind of variable as always let's go with require and we're looking for http that's the module name and the method we would want to use is create server again we'll assign this to some kind of variable and in this case the variable name will be server then we go with http create server and this create server method is looking for the callback and in that callback function we have two parameters and both of those parameters are objects and since they're parameters you can call it whatever you would want but a common practice is calling them rec and res now this first parameter represents the incoming request so imagine a client is requesting from the web browser your webpage so you'll have information about the method and all kinds of useful stuff in that request object and the response is what we're sending back now we're not done of course we'll set up more code here but before we do anything we also would need to specifically say what port our server is going to be listening to and that's why we'll go with server and listen so that's another method and again this is arbitrary but i'm gonna go with 5000. again if this looks like a lot of gibberish where we have the request response as well as the ports don't worry later in the course i'll cover that in more detail as well as show you some useful slides and all that good stuff and as far as the response well we have few methods we have write so we go with arrest and again this is the object and notice here how i'm not using the rack yet so i'm not checking for anything i'm just concerned about my response and the method name is right and inside the right we just come up with some kind of text and i'll say welcome to our homepage homepage and once we have sent back the response i also would wanna end my request so i'm gonna go with res.end and once we're done setting up the code inside of the callback function now of course i would want to open up my terminal clear everything and we would need to spin the sucker up and of course the way we do that is node and then objects since that is the file name make sure that you save it though so before i run i'll save it and then notice something interesting notice how we're not exiting so previously every time we ran the file every time we ran node and then whatever the file name we exited from the file right so node was done executing the code and we just moved on now in this case since we have a web server what do web servers do they keep on listening for requests and actually you want your server to always be up and of course if i go to my web browser and then i'll make this bigger and if we go with localhost and of course in this case we have 5000 there it is we have welcome to our homepage so now of course we have effectively created our first website now granted it's very basic but at least we have something on screen and before we discuss the external modules and actually set up a module that nicely watches our code and does the restarts for us i also want to showcase what we have in the request object now this is going to be a giant object so i'm not going to cover each and every property however i would want to showcase a property that gets us the url and what would be the url well that would be an address and if you're worked with reactor or dom you know that for example for the homepage we used forward slash and then if the client wants to go to for example about page he or she would enter forward slash and then the about now in our case notice how we're still serving the same content so just to give you a quick introduction of the request object as well as set up a bit more realistic application we're going to go with the request now again if you want you can log it so we're going to go here with request and you'll see that it is a giant object now since we made some changes we do need to stop it and then we'll go with node object but notice how we're not right away console logging the request object why well because server is waiting for those requests so we need to go back to our browser and then refresh and then of course once we navigate back like i said this is going to be a giant object which bunch of useful info now what we're looking for is the url property because that url property is going to tell us well what address client is requesting so what endpoint the client is requesting and like i said for the home page the common practice is using simple forward slash so in here we can set up the if statement where i say if request url is equal to the home page then of course this is what i would like to send back and just to speed this up i can tell you that we can cheat a little bit where we can just place everything in the end and in my case i'll just cut out my string so we have res dot end so now we simply send the text and now of course i also would want to check for the about or contact or whatever so in here let's go with if and then request and url and if that one is equal to about about then of course i can send different text and as far as the text i'm just going to say here is our short history and then lastly well what happens if the user is trying to access a resource that doesn't exist on our server so we'll have the about page we'll have the home page what about if the user is asking for a contact page that we don't have well here we'll simply set up a default response we'll say res that end and just to make it interesting i'll set up the template string and i'll show you that if we really want to we can also pass indirectly html and i'll say oops an explanation point i'll close my html again please understand this is just a basic scenario of course that's not how we'll be setting up our apis or nothing like that but just to give you a quick intro we'll do it quick and dirty where there's going to be a paragraph and we'll say we can't seem to find the page that you're looking for page you are looking for looking for and at the very end i would want to set up a link that allows the user to navigate back so go with href and i'll say forward slash which just means home page and we're gonna go back home let's close our link let's save that one so at the moment of course we have the about and by the way almost forgot yes we do need to stop the server and we need to go with node and then app.js refresh one more time there it is notice how we don't have the about we can't seem to have the page you're looking for and that is actually a bit interesting because it should be available right and of course the reason is because i messed up on the url property my bad let me do this one more time and we'll stop the server here again let's run node app.js and now we should have here's our short history that's our about page then we have the homepage and of course you already familiar with our error page so if i'll go with error or any kind of resource that doesn't exist then of course we'll get the error page and of course we can bravely navigate back home and we go back to our home page that should do it for the quick intro of base modules and now of course we are ready to move on to our next topic all right at this point we're familiar with two types of modules our own as well as the nodes built-in ones but just like in any good infomercial i'll say but wait there's more we also have access to the world's biggest code store and before you seriously start questioning my mental state imagine this scenario you're building an app and of course as any good app it needs to have a slider just for funsies now at this point you generally have two options build it from the scratch yourself or search on google and copy paste someone else's solution well have no issues with either of these options keep in mind that someone somewhere has struggled with the same issue the need for the slider and there's a good chance that that person was kind enough to build it and share the whole project with us so our only job is to go through the docs and with the help of one command just add it to our project we can do that because when we install node we automatically also install npm or node package manager and npm enables us to do three things reuse our own code in other projects use code written by other developers and lastly share our own solutions with other developers as well the npm project is hosted at npmjs.com again the site is npm.js and here you can find everything starting with useful utility functions to full-blown frameworks and libraries and as an example if you're familiar with react you know that react has the create react app package and of course it is hosted on the npm a typical node project will have more than few npm packages installed as dependencies and before we install some cool packages let's talk about naming npm calls the reusable code a package and a package essentially is a folder that contains a javascript code now another names you'll hear are modules and dependencies and honestly at this point all three are used interchangeably when talking about shareable javascript code so don't be surprised if during the course i call them any of these names package dependency or module at the end of the day they all mean the same thing lastly let me just mention two things first there is no quality control in npm registry anyone can publish anything so it's up to you to sniff out the empty and useless packages and yes there are quite a few of those ones out there as well a good indication of the security and usefulness of package is the amount of weekly download if the number is high meaning if it's popular it's a good chance that it's a battle tested and ready to go and that brings me to my second point remember the slider example we discussed in the beginning of the video when it comes to npm packages there's a good chance that if there is a bug someone else has already fixed it and as a result it's already fixed in the package or there's a working solution all right so that you did for intro let's start using node package manager in our own project and as a side note if you want to search for some packages just visit npmjs.com and then for example if you're looking for the bootstrap you'll find the package and of course you can click on any of them this will bring you to the docs as well as weekly downloads and rest of the stuff once we're familiar with node package manager let's see how we can start using it in our own project and the good news is that it's much simpler than you would expect you see when we install node we also install npm and because of that we have access to npm global command and you can check the npm version by running npm version in your terminal just keep in mind that the version most likely won't be the same as your node version and that is totally okay so you can either do that in the terminal or of course in the integrated terminal and you can simply type npm and then hyphen hyphen version i believe you can also check by hyphen hyphen v and there it is of course now we have the version for our node package manager and then we have two flavors we can install package as a local dependency and that just means that we'll only use that package in this particular project that we're working on and the command for that one would be npm install or i for short and then whatever is the package name so whether that is bootstrap low dash express or whatever or we can install dependency as a global dependency and that just means that we can use it in any project and the command for that one would be again npm i or install whichever method you prefer and then hyphen g so this is going to be the flag and then again the package name now when you install something globally most likely on a mac they will ask you for the sudo so you'll have to provide the credentials that's why you'll run sudo npm install and then hyphen g and again package name as far as which one you'll use more often that definitely will be a local dependency flavor because even though yes you can install packages globally with arrival of npx there's actually less and less need for setting up something globally that's why we'll focus on local dependencies first how to set it up in our project and then in a few videos when we talk about npx i'll cover why there's less need for setting up something globally now there's one more thing that we would need to set up in our project as far as dependencies so i know i know you're eager to start installing the packages but let's just wait a little bit and next video we'll add that extra thing that we're missing right now and then we'll be in good shape and then we'll start installing every package under the sun excellent we now know that we have access to the npm global command we now know that in order to install the local package we will need to run npm i and the package name so what are we missing well we're missing file by the name of package.json and essentially you can think of it as a manifest file that stores important information about our project and there are three ways how you can create package.json first is the manual approach where you just create a package.json in the root and please do that in the root if that's something that eventually you decide doing and then of course you would need to create each property or there are two ways how we can automate this and the first one is running npm init and in there they'll just step by step ask you the questions and if you want to skip it you can just press enter and the another way the third way is running npm init with a y flag and then everything is set up as default so i'm not going to show you the manual approach it's just too time consuming and we'll right away go with npm in it first i'll show you the step by step approach and then of course i'll show you how everything is set up by default using the y flag so go to your terminal and just type npm in it and there it is of course now they tell you that there's going to be a walkthrough of creating a package.json file and the first one is the package name and by default of course it is going to use the folder name now keep in mind that if you eventually want to publish this package then the name has to be unique so you need to make sure that nowhere in the npm you can see the package with the same name and i'm just gonna go with tutorial as far as version we'll talk about versions shortly so i'll just skip this one as far as description whatever again is just the default now as far as the entry point eventually will change it but for now it's good enough we're going to go with one intro js and then the test command as well as git repository and keywords and author and license and we simply say yes and we are in good shape so now of course we have the package json file with name version description as well as the main property and of course the scripts author and the license now i'll remove it i'll say delete and i'll show you that of course you can skip all those questions by simply typing npm in it and why and as you can guess yes of course you can come here later and then just change these values that's why it's definitely faster to just type npm in it and then the y flag so why do we need this package.json well because if i would want to install the package the local package now of course this package is going to be stored as a dependency and to show you that let's just go with npm and you know what let me clear the console first so we're going to go with npm i and then we're going to go with the package name lowdash and if you're not familiar with lodash it's just a utility library and i'm just specifically using for installation purposes there's no real reason to have low dash for our own project but it's just something pretty interesting that i would want to showcase that's why we're using lodash and we run it and notice how we installed the package and check it out now in the package.json we have dependencies property and it's an object and inside of that object we have a package by the name of lowdash now i'll show you in this video or maybe in the next one why it's so important to have this package.json but another thing that i would want to showcase once we can see that we have dependencies property if you go in your visual studio code and if you click on refresh explorer what you'll also notice is this node modules folder and in that node modules folder this is where all the dependencies are stored so if you don't have that folder already and pm creates it so in our case of course we didn't have any dependencies so when we install that first dependency npm creates that folder and this is where you'll find the dependencies now notice something interesting where for the low dash we only have one folder right so we have only one dependency but when we need to keep in mind that of course there's going to be some packages that have other dependencies and that's why i first installed lodash just to showcase that yes once you install dependency of course it is going to be in node modules but if you'll try to install a package that is bigger that uses other dependencies you'll notice something pretty cool where if i clear my terminal and if i'm gonna run npm i and then bootstrap again you can use any other package you'd want this is just to showcase how the packages work we won't use the bootstrap in this project so once i install and once i refresh check it out not only i have low dash not only i have bootstrap which i installed but since bootstrap is using jquery as well as the proper js now these are installed as dependencies and if you take a look at the dependencies property now of course we have the bootstrap as well and again the whole point of this video is to showcase why we need package.json so we need it because we need to provide information about our project and inside there a very important property is the dependencies one because in there we'll just store the dependencies which our project is using and then some packages are actually going to use more dependencies and they will be automatically installed as well in our case that was bootstrap and just to give you a taste of the package why don't we just navigate to app and i'm going to do that below the comments of course you probably would need to clean the file and as a side note the last module the http i saved in file by the name of 12 http and back in the app.js in order to start using the module in our case i guess i'm gonna go with low dash first i would need to set up the variable and common convention is calling the variable like so and we'll set it equal to require and now of course we have access to the low dash now this is the difference between node packages like for example the http or the file module or whatever and the ones that you install the external ones the external ones you always have to install first if you won't install the dependency well node won't be able to find it so in our case we did install the dependency the lowdash so now of course i can just assign it to the variable and since lowdash is utility library why don't we test out one of their methods and i'm just going to go with items and i'll create an array of arrays so items is going to be an array however the items are going to be arrays itself so two and three and then we're gonna go with four and low dash has this method the flat and deep method that effectively will just spit this back as a flat array and the way we set it up we just go with const and i'll call this new items and then since we have access to everything in this variable now i can simply go with underscore here dot and then flat and deep so flatten deep and then we'll pass in the items and now if we console log new items and if i go to my terminal and just type node app.js and by the way i need to save it so let me go back i'll say node app.js and once we run check it out in a console i can see of course the one two three four so lowdash has the method by the name of flattendeep we have access to it because we install it as dependency and now of course i can start using it now we're not gonna use bootstrap in this project because that would be too time-consuming bootstrap was just used so you can see that some dependencies will have more packages so once we install one dependency there's actually going to be more dependencies and hopefully you have a clear understanding of how you would set up package.json how we would install the package and next video i would want to showcase why having package.json is so crucial and so beneficial when we are starting to share our project with other developers awesome we have package.json we installed few dependencies and now i want to cover why having package.json is so crucial when we start sharing our project with other developers and for this example i'm going to use github as well as few basic git commands and my assumption is that since this is somewhat of a advanced course you're already familiar with git and github and you have the account if you don't please stop the video create the account and just use your favorite search engine to learn about the basics of setting up the github repository as well as basic git commands so our task is to push this up to the up and now million dollar question are we just pushing everything up including the mode modules which for the most projects is going to be somewhat big i believe i just checked in our case it was like nine megabytes but trust me it always gets way bigger than that or we would just want to send the code and you can probably already guess that since i'm implying that the size is too big that we'll have to push this up to the github without the node modules and we'll start by creating a dummy repo on a github so let me open up a new window i'm going to go with github and i'll just create a temp repo and then i'm just going to create a repo and i'm looking for these three commands essentially i would want to get that url the remote url so i know where to push it and then inside of the repo before we set it up as github repo first i would want to go with new file and we'll create a git ignored because of course what i would want is to place the node modules in a git ignore file because that way they will be ignored by my source control and i won't be pushing up this giant folder to the github because you'll see in a second that there is no need for it so we're going to go with forward slash and then node modules and if you're not familiar with git ignored it's just a file that specifies which files are going to be ignored by the source control and in our case as you can see i'm placing node modules inside there then i'll clear my console and i'll just initialize this as an empty git repo and then we'll add everything so git add git commit we'll just say first commit first commit and then i'll copy and paste those three commands in order to set up that url the remote url and once i have this in place should be able to go back to my github and there it is this is my repo now probably your next question is okay so we pushed it up to the github but i can clearly see that in my app.js well technically i'm using the load as dependency right but we didn't push up the node modules folder so how the person who is going to get this repo will be able to run the code in the app.js since there's no node modules and you told us previously that we can only run it if the dependency is there well let's check it out i'm going to go with clone option so i'll just get the url i'll navigate back here and i'll do that in messed up again it doesn't really matter we're just going to go with desktop and then git clone now i copy and paste the url i'll open up a new instance of my text error copy and paste and this is where the magic happens if we have package json we simply need to run npm install and what is going to happen the npm will check for dependencies that we have in the package.json and automatically set up that node modules folder so if i go here first of all i can see that there has been some changes that is already good news that just means that i have my node modules and if i refresh check it out so now of course i have my node modules folder and if you have been using react applications you're probably already familiar with this one where again when you are setting up the code you're not sharing the node modules folder and i can showcase that by taking a look at my react projects and that's not what i wanted i didn't want to look at my awesome picture what i wanted is react and then let's go with project and you'll see that in that repo we have bunch and bunch of folders and each folder has two more folders final and setup and now check it out none of them have the node models because imagine the size of this sucker if i would push for every project for every folder the node modules instead i have package json so when you get the repo when you clone the repo or download or whatever then of course you get the package json and in here these are the dependencies and you just run npm install and they are being installed okay hopefully it is clear that why it is so crucial to have the package.json because we can just share the code without dragging the massive node modules folder with us we can simply just provide what packages our project is using and then once we get the repo then we just run npm install that is the command and then npm will install all the packages that are in the dependencies awesome we're familiar with npm we're familiar with package.json now let's finally install the dependency that we'll use for the remainder of the course and that is no other than the node one and of course if you want to get more info you can visit the npm and you can search for the package but as far as the general setup is just to watch our files and then restart our app for us so that way we don't have to each and every time type node and then whatever the file name and we can install it as a simple dependency that is definitely an option but since i also would want to cover depth dependencies we'll install that as a depth dependency and the command for dev dependencies is following where we go with npm and then i or install whatever and then we go with nodemon so that is the package name and then you can either do hyphen d so that just signals that that is a that dependency or you'll see this save and dev so again whichever method you choose that is really up to you but just remember that both of them will save it as a dev dependency so let's install it and then i'll talk about it why we would want to set up as a div dependency and the reason for that is because if we think about it do we really need nodemon in production and the answer is no when we push it up to digitalocean or heroku or whatever we'll of course use something more serious than nodemon to restart our application pm2 comes to mind but while we're developing yeah that is an option so in this case we'll add right away nodemon to the dev dependencies now what else what kind of packages we would add to dev dependencies for example testing packages for example linting for example formatting and that sort of thing again nothing stops you from jamming this in dependencies but if you think about it it makes way more sense if we add this as dev dependency so we use it while we are creating the app but then once it's in production then we just share the dependencies that actually the app is using not the ones that we used while we developed the app hopefully that is clear and once we have the package we're almost there now we just need to understand how the scripts work in a package.json and at the moment as you can see we have the test one we won't use that one and inside of the script object we just set up the commands and as a side note we can set up the command right now even without the node mod for example i could go with start and that command will be equal to npm and or i'm sorry node and then for example app.js so that is my command and once i save my package.json instead of running this node app.js i can simply run npm and start and there it is as you can see same functionality i run app.js and i get back the array as well as the hello world again we still exit the application so it's not like we're out of the woods but i'm just showcasing that yes we can set up the commands and then in the command we just provide a value and in this case of course it is node and app.js now for some commands you can simply type npm start as you can see but for some of them you'll have to provide the full value and that is going to be npm run and nor to showcase that i'm going to go with dev and that one will be equal and here we're gonna go with a node mod and then app.js so instead of running node like we're doing in the start now i'm setting up a dev command and in order to run this one i'll have to go with run and then whatever here's the command name again some of them you'll be able to use the shortcut where you go with start and some of them you'll have to go the full route with npm run and then whatever is the command and as a side note yes you can still run npm run start and this is also going to invoke the command but in our case we have dev and in here i have nodemon and then app js so let's try it out let's say first the package json and you should notice something pretty cool where if i go with npm run and dev now i'm spinning up the node one and it tells me that nodemon is watching my application and since i know that of course we can test it out where i'm gonna go with console.log and then instead of the hello world which i have after new items i'm gonna go with hello people and you should see something interesting where once i change the text yep nodemon restarts my app and now of course my value is hello people awesome so now i don't have to type every time the node and then whatever file name nodemon automatically just restarts my app and i simply set it up as a script now if you want to change this around if you don't want to run npm around dev you can simply say nodemon and then app.js and just remove the dev1 completely and a side note again if you have worked with react project you are familiar with the setup because for react again we run npm start and then there's a value that spins up the whole react dev server where we can see our application not bad not bad well we're still on a roll let's cover how we can uninstall the package as well and as a side note if you want to stop the nodemon just press again ctrl and c and notice how we're of course stopping the nodemon and again if we want to spin up we'll just go with npm start and as far as uninstalling the package we have the command for that and the name is uninstall so i'll stop the nodemon and in the terminal i'll type npm uninstall and then of course the package name which in my case is going to be a bootstrap now this is one of the approaches how we can do that and there's also a nuclear approach now why i'm calling this a nuclear approach because that way we remove the whole node modules folder and don't worry once you run the npm install then of course you set everything back up from the scratch as well as you would remove this package like json and don't worry i will cover the package.json file a bit later and the way that is going to look like well we can first clear the terminal i'll install the bootstrap from the scratch again so say bootstrap here and by the way probably need to add npm i and now again as you can see i have it as my dependency and then like i said the nuclear approach is removing the node modules yep and then removing the package log and then just running npm install now of course in the package.json if i want to remove the bootstrap for example in this case i can simply remove it from my dependencies so i just remove it in the package.json then clear everything and then we go with npm and then install and now we'll get from the scratch the node modules since we're the ones who removed it and also we'll get that package hyphen lock json now i'm showing you that nuclear approach because if you have used gatsby you know that cats be somewhat notorious for sometimes just being a little bit annoying where you do need to remove the cache folder you do need to remove the node modules as well as package lock and then once you start up everything from scratch then as a magic the gatsby app starts working and check it out if we take a look at the node modules now yes there's a bunch of modules that nodemon is using right but there's no bootstrap and i can clearly see that because there's nothing under the letter of b so we can clearly see that we removed bootstrap from our dependencies all right and now let's take a look at how we can install package globally and what would be some of the use cases and first let's start with command let's jog our memory command was npm install and then dash g and the package name and in mac they might ask you for permissions so you'll have to start with sudo and then again same spiel npm install blah blah blah and first i want to showcase that i haven't installed nodemon globally and the easiest way for me to showcase that is by running nodemon and app js so we'll try to install nodeman package globally why well because then i can use nodemon in any of my projects at the moment i have it as a local package and of course i can spin it up by running npm start but let's imagine scenario where i have i don't know 20 nodal applications and i'm constantly working on node applications so to make my life easier i will install node 1 globally and then i won't get this error because at the moment you can see command not found normal all right so how do we do that well we can install it in our terminal or we can do it in the integrated thermal it doesn't really matter when it comes to global packages you can install it from anywhere so in my case i'm just going to navigate back to my terminal just so you don't think that i'm cheating and i'll zoom in and we'll simply run and by the way i need to start with sudo and then npm install and hyphen g and of course we're looking for nodemon so now of course i'm prompted to enter my password and once i enter my password of course i'm going to install nodemon globally and now in any of my projects i can simply go with command of nodemon and then whatever is the file name now to show you some of the use cases if you work with gatsby you know that they have the global gatsby cli tool and that was one of the reasons why you installed something globally is because well you used one of the frameworks for example react or gatsby in this case and then of course in order to set up the gatsby project or react project you needed to install this globally now things have changed though with arrival of npx and i'll talk about the npx at the end of the video but notice if you navigate to your react docs and if you look for create react app which again was something that you needed to install globally now they suggest this npx route where essentially you go with npx and then again whatever is the command name for example for create react app that would be create react app for strappy the headless cms that would be create strappy app and hopefully you get the gist where for every resource that of course would be different and with that command you don't have to install that tool globally for example again in our case we're installing nodemon but normally prior to npx you would install this create react app globally and then you can spin up those react projects now i'm going to go back to my terminal as you can see i was successful so what's going to happen if i go back to my project and if i run nodemon and app.js since i have installed that package globally there it is i spin up my app.js and if you don't believe me i can change it back to hello world and i have no issues hello world and there it is now of course i have hello world e in the console so hopefully it is clear that yes we can install packages globally and yes one of the biggest use cases was working with some type of front-end library but with an arrival of npx things have shifted where now those libraries suggest using the npx route instead as far as my personal preference since i'm recording a lot of courses and since some of the global packages usually introduce some kind of bugs to the students now not for all the students but there's always this one student who just has a lot of issues with the global package personally i avoid them as much as possible so i always either use the mpx or i just set it up as a local dependency again it's not a rule you can do whatever you would want but i'm just telling you what is my preferred option as far as what is npx it stands for execute and official name is the package runner it is a feature that was introduced in npm 5.2 and again the main idea is following where you can run that cli tool for example in this case create react app without installing these globally so as long as you have npm with a version of 5.2 or greater instead of doing this whole spiel of setting up the cli tool globally you just go with npx and then whatever here is the tool name and of course the last one is the folder name as far as the package log json why do we need it well if we take a look at our dependencies we can see that they have versions and if you remember some of the dependencies have dependencies on their own and of course we need to keep in mind that those dependencies have versions as well and for example the person who gets your project you probably want them to have the same exact setup because keep in mind as these versions change well so does some of the functionality correct so for example you set up to your whole project you use some kind of dependency that uses some other package and that version changes not for example for the bootstrap but for the jquery and then pretty much your project is obsolete meaning it might get some bugs because the version of the jquery changed so that's why you have this package.json and in there you have those specific versions for all the packages not only for dependencies but also for the packages that the dependency is using now as far as this version we have three values and you can think of it as a contract between us the people who are using the package and the person who is creating and first number is a major change so when this changes that means that there are some breaking changes now the second one is a minor one so that means that it is backward compatible so for example if this changes to 18 i shouldn't expect any breaking changes and the last one is just a patch for the bug fix so that's also something to keep in mind when you decide to publish your own package that of course that's why we have here this version now lastly i would just want to mention that if you're interested in more info about the package.json i would suggest this resource so i simply went with package.json then keep on scrolling keep on scrolling and you're looking for i guess this blog post right so the name is the basics of package.json and in here you literally find everything explained to the smallest detail whether that is a name version and rest of the fields that you can find in a package.json beautiful we now know how to utilize npm and for starters as a result for the remainder of the course instead of frantically typing node.js in a terminal we'll simply spin up nodemon and it will watch for the changes and restart the app for us now what before we move on to creating servers with express.js there are a few important node topics i would like to cover first and those topics are following event loop async patterns in node.js events emitter and streams in node.js while these topics are extremely important please keep in mind that our goal is to only understand the general ideas behind these concepts and i only introduce them so you have an overall understanding of how things work in node.js before we build our first node.js app if you're not satisfied with my explanations or simply want to do more research by yourself just type any of these terms in your favorite search engine and i can guarantee you'll find plenty of useful resources within a matter of seconds like blog posts youtube videos and conference talks with that said it's my strong opinion that it might be easier to understand those concepts more deeply so not just a general understanding but understanding them more deeply once you have one or few working node apps under your developer's belt let me also mention that in order not to waste your time with time consuming setup in few upcoming videos i will run some pre-built code let me be very clear though i'm only going to do that in a few videos and for the remainder of the course we will type out everything together all right and let's kick things off by discussing the event loop now event loop in node.js is one of those topics where i could spend the entire course discussing it and it still wouldn't be enough so let's try to avoid that and instead just understand the journal concepts while there are tons of useful event loop explanations out there the one that i probably like the most is this one the event loop is what allows node.js to perform non-blocking i o so input and output operations despite the fact that javascript is single threaded by offloading operations to the system kernel whenever possible and as you can see i'm reading straight from the node docs now don't beat yourself up if this sounds like a lot of gibberish there's a reason why one can dedicate the entire course just for event loop it is a pretty complex topic but one word i do want you to remember is this offloading and you'll see why in a second also don't worry i have prepared more examples as well as some slides to get my point across but just in case you're not happy with my examples or you just want to explore the note event loop in greater detail here are a few external resources i find particularly useful when it comes to blog posts just go to your favorite search engine and type node.js event loop and the one that i find really useful is this one and the resource is nodejs and not.org but it is dot dev and then follow the link and here they cover event loop in great detail with a lot of cool examples and pictures and slides and all that good stuff and when it comes to videos i would suggest going to youtube and then just type event loop and the first video that's going to pop up is going to be the event loop bot in browser javascript and i'll talk about it in a second and the nodejs specific event loop video is this one i believe it's 15 minutes long and you can see the name over here so this is a very very useful video where the speaker covers a lot of useful details about node.js loop in great detail and the reason why i'm suggesting the first one as well well what is the language that we use in node that of course is javascript right and even though there's some differences between the event loop the one that we use in the browser and the one that is in the node.js if you understand the concepts behind the event loop that we use in a browser trust me you're already halfway there to understanding how the no js event loop works since it's such an important topic like promised i have prepared some of my own resources as well we'll start with the slides and move on to the closed examples in next video as a side note i made all the course slides available on course api.com again their website name is coors api.com and once you click on the slides link you'll see all the slides and i would want to start our discussion by taking a look at what it means that javascript is synchronous and single threaded and effectively it's just a fancy way of saying that just repeat everything line by line so for example if i have console log with first task then i have a for loop that takes some time in this case two seconds but that could be 10 seconds that could be 20 or whatever and then i have another console log of next task javascript will just start reading everything and it will read it line by line and if this takes a long time it will only run the next test once it's done performing this time consuming one so hopefully that is clear that javascript just reads everything line by line and now let's take a look at our second slide and in here we can see the solution if we would want to offload something to the browser so when we're building browser javascript apps we have this option of offloading to the browser now of course it doesn't mean that we can offload the for loop that's not going to work this effectively is still going to be the blocking code but browser nicely provides the api where we can offload those tasks to the browser and only when the task is done then we execute the callback and probably the example we have done the most is the fetch essentially when we make the network request but we can also do that for example with a set timeout so i still have console.log with first task but then even though my set timeout function has the second argument of zero so essentially i have set timeout function i provide the callback function that's going to be executed in certain amount of time even if this is zero meaning you would expect this one to run right away it only runs after the next task so once javascript is done executing the immediate code only then it executes the callback so in this case we have the set timeout the api that is provided from the browser and we just said that we would want to execute that e in zero seconds so effectively there is no wait time however javascript will first execute this code and only then will execute the callback so that way we can offload those time consuming operations to the browser again it doesn't mean that we can offload for loops it means that browser does provide some apis where we don't have to write the blocking code now let me be very clear though when i say we cannot offload for loops what i mean is that we can still write blocking code in javascript but the browser does provide some nice apis where we can offload those time consuming tasks and that brings us to our main friend the nodejs event loop again before i go over the example let me stress something event loop is somewhat complex and this is just to give you a general understanding so let's imagine this scenario i have an app and just like any cool app i have subscribers or users or however you would want to call them and in this case since my app is so so popular i have eight of them and what do the users do well they're probably being annoying and they're requesting something from the application and as the requests are coming in the event loop is responsible for avoiding this type of scenario so let's imagine this i have all these users the requests are coming in but larry the little decides that in his request there's going to be some kind of time consuming i don't know database crawl or something like that so effectively he's requesting something and behind the scenes in my code that means that i need to perform something that takes a long time so in this case the event loop just registers the callback so it registers what needs to be done when the task is complete because if the event loop wouldn't do that then we would have this scenario where the requests are coming in and because larry is requesting something that takes a long time the rest of the users would have to wait and essentially it's not that the actual operation takes a long time it's just the fact that we're wasting our time on waiting for that operation to be done and only then we can serve the other users but what the event loop does it registers the callback and only when the operation is complete it executes it now keep in mind that again we're not executing this right away when we can effectively it's the same scenario where we run our immediate code first and only then when we have the time we execute the callback so for example in this scenario if i would have hundred console logs after the next task i would run them first and only then the second task would appear here regardless of what is the time set in here because again we're running our immediate tasks first and only then we run the callbacks so the same thing happens here where the requests are coming in let's say that the operation is complete we first registered the callback operation is complete and instead of executing that callback right away it effectively gets put at the end of the line and then when there is no immediate code to run then we execute the callback hopefully that is clear event loop is our best friend because with the help of event loop we can offload some time consuming operations and effectively just keep all our users happy all right and once we have looked at the event loop in theory to hammer this home let's also take a look at some code examples where we can see event loop in action as a side note all code examples are located in the event loop example directory so if you need to take a look just grab the repo and you can find it there and you should be familiar with our first example since it's a async version of read file method so we import read file from the fs module and then we have console.log started our task first then we have read file method where we pass the path we pass the encoding and then of course we have the callback and then in the callback i cancel logged first result and then of course i have completed the first task and then right after the read file i have starting next task and something really interesting in a console i can see that we first cancel logged started the first task then i right away have starting the next task and then of course once i'm done once i get back my result then of course i have hello this is first text file and of course completed first task and again the reason why is this happening because read file is a synchronous and we already know that event loop will offload this in this case to a file system so we start reading the file notice like okay run this line of code then offload this one and only when i get back to the result then run the callback so when the file system responds with error or the data then we invoke this one all right so we offload this task and we just keep on reading the code that's why we have started the first task starting the next one so right away go to the next test and this one this asynchronous one well we're just offloading and then once the response comes back whether it's an error whether it's a success only then we invoke the callback hopefully that is clear now as far as this comment i only added this one because we need to keep in mind that of course i'm just grabbing this code from the file but the file is sitting in the folder so if you were to run nodemon and then directly the filename which is of course going to be in the event loop the path won't match so this path only matches because of course i have app.js but if you'll try to run this code directly in this file that's why it's not going to match and you need to go one level up now my assumption is that you're running it the same as me and you're running that with npm start that's why i kept the path matching to the one in the app.js now our next example so let me clear my app.js i can close the read file as well as package.json and then the next one is set timeout so select here everything and copy and paste in my fgs i'll restart and then i have two console logs and the third one is e in a set timeout and this is pretty typical example for javascript loop as well if you have taken javascript courses which again i assume you have since you're watching the note one you probably remember this example where i got you here is following yeah i have the console log first and i have the second and third and you think that since set timeout is set to zero so since we're saying yeah call this callback function but actually wait only zero seconds you'd think that the order would be first second and third right well wrong because we have first third and second why well because set timeout is asynchronous correct and what happens with asynchronous well they get offloaded so in this case we run first third and then the second because this one gets offloaded again this one goes to the back of the line and only when we're done with our immediate code pretty much with our synchronous code only then we invoke that callback all right now i also added these comments here where i have started operating system process and then completed and exited the operating system process and the reason why i'm showing you that because in next two examples we'll do something a little bit different so now i would want to go to set interval and by the way it's going to be a bit clearer if we run here node and then app.js so let me stop this and i'll go with node and objects and you'll notice that we started the operating system process and then the moment we're done with the code that's it we exit now if we'll take a look at the set interval you'll notice something really interesting where if i go with node and app.js notice something interesting and by the way of course i didn't copy and paste so go to the third example and then just remove all this code and copy and paste so that's my third example and in here i have the set interval now again yes we'll have to run few times node app.js and now check it out so what i see here is i will run first so that's my console log and then i have the set interval and notice how we're not exiting the process here so we start the process similarly to the second example but if in the second example we actually exited because we completed all our tasks in this case we're not doing that why well because set interval is asynchronous now the difference between the set timeout and set interval is the fact that set interval runs in those increments in this case of course it is those two seconds so every two seconds the event loop is just gonna invoke that callback now that's why we're not exiting that's why we're still in the process and we can only exit the process if we kill it so that would be control and c or there's some unexpected error otherwise it will always stay alive now again keep in mind one thing where notice i will run first was first why well because again this is asynchronous and i know i've said this before 20 000 times but again this is probably the core building block of no the fact that every time we have some asynchronous action it's just going to be offloaded and then when it's time we invoke the callback and our last example is a server and again i just wanted to showcase how the process stays alive so i'll take all the code and copy and paste in app.js now i'll stop this one so stop the process and then we'll clear the console and again just to showcase how the process stays live i'm going to go with node and app.js and i'm doing that so you're not confused with nodemon and then check it out so we have server listening on port 5000 and then every time the request comes in well we invoke this callback and in our callback we're simply cancel logging request event and then we send back the hello world so now if i were to go to a localhost 5000 there it is i have the response of hello world and in a console i'll see this request event and check it out how again this process stays alive why well because listen is asynchronous and the moment we set it up now event loop is just waiting for those requests to come in and then once they come in then of course we run our callback now please don't confuse this callback with what we're responding our request i went so this callback is just when we're setting up the server because in here we can have the success over there so in our case as you can see everything went great we have server listening on port 5000 but of course there also might be an error and this one of course just responds to that request event but the whole point is with server.listen we just say hey event loop just keep listening for those incoming requests and the moments show up then respond to them appropriately hopefully it is clear and of course we can move on to our next topic all right and up next i want to talk about asynchronous patterns in node.js so if we remember when we were setting up the file system module we covered how we have two flavors we have the synchronous one and the asynchronous one and while asynchronous one is great since we're not blocking the event loop the problem is that if we're using this callback approach well it gets messy pretty quickly right because we're nesting one callback inside of the other one so now in the following videos i would want to show you the alternative that we'll use throughout the course and why in my opinion it is much cleaner syntax and that's why of course we'll use it and first what i would want is just to kill everything here and i'll start with the nodemon since i'm done showing you the event loop and we're just going to go with npm start right that was the proper one and now i'll delete everything that i currently have not here sorry so i'll leave this one the async one i would want to remove everything in the app.js and now i just want to quickly show you the code that would block that event loop again this is going to be the video where if you don't want to code along you don't have to you can just sit back and relax and effectively you'll be in good shape and again we'll set up the server like i mentioned before already 20 000 times don't worry about specific commands we have rest of the course where we'll be building servers so trust me you'll get sick of it so go with http and require and of course we're looking for http module and then remember the methods create server and listen so we go with const and we create the server that is http and create server we pass in callback a callback takes two objects request object and response object so again essentially request object is what is coming in and response object just represents what we're sending out what essentially we are responding and then i would want to listen on a port again so i run server.listen and then i'll pass in the port of 5000 and then of course we have that callback once the server is ready and in here we can just go with console.log and we'll simply say server is listening on port 5000 server is is listening or just listening listening on port and then of course in my case port is 5000 let's set that up so we should have this listening on port 5000 and then of course in my callback function i would want to check 40 urls because i want to show you how even if we try to get a different resource we're still blocked by other user if he or she is requesting some kind of resource where we have the blocking code and don't worry if this sounds like gibberish you'll see what i mean in a second so remember on the request object we could check for the url so effectively you could check what is the resource that the user is requesting so for example home page would be forward slash and then the about page would be forward slash and about and that is sitting in the property by the name of request and url so request is the object and then url is the property so again we'll do a quick and dirty way we'll just say request url is equal to a forward slash that means it's a homepage and then we just need to go with a res.end and then we'll say home page again later we'll have way more sophisticated approach but for now this will do and then we're checking for the about page okay awesome so this is going to be an about page and then if there's a page that doesn't match any of the resources then of course i'll just send back i don't know error page i'm not going to set up the whole link nothing like that all right we save it and then this should send back about page awesome and then of course in home page i can just respond with the homepage so life is beautiful users can come here and as a side note multiple users i'm representing with these tabs so imagine these are my users and life is beautiful we are requesting resources and we're just going on about our day now the problem is going to be if i go to about and if i set up some kind of blocking code now what would be a blocking code well that could be a nested for loop so i'm just going to go with blocking code and then i'll add some exclamation points and let's simply set up a for loop let's say i is equal to zero and then let's say i is less than thousand and yep i plus plus so every iteration will increase by one however i'll set it up as a nested portal so copy and paste and i'll just change these values to j so j here and j here and then let's just cancel log and we'll say j and i again doesn't really matter what we type there just say i and j now known dialogue question what do you think is gonna happen so if the user navigates to about i mean we can kind of see that this will take some time right now you would expect though that only the user who navigates here gets blocked and you'd be wrong because we'll also block the other suckers who are just trying to get to the homepage so let me navigate here and check this out so i run this one and notice how we're loading now the same thing happens here now and here okay and only when we're done here then these two can get the resource again now of course if i go to my project i can see that in the console i have all these values right because i have this blocking code i have the synchronous code that just takes a long time and this is just a representation of why we prefer this asynchronous now yes at the moment this is messy and don't worry in the next videos we'll fix it but this hopefully gives you an idea why you should always strive setting up your code asynchronously because what we've learned in the previous videos if we do that then those tasks are offloaded and then only when the data is back only when it's ready then we invoke it and that way we're not blocking the other users hopefully it is clear and now of course let's take a look at some other patterns we can use so we still get the benefits so we're not blocking that event loop but we also have a cleaner code where we don't have this nested callback mess all right and once we have covered why it's so important to use the asynchronous approach now of course let's clean up our f a a sync so instead of using these nested callbacks let's see a nicer pattern and as i say note if you want to see the code that we wrote in a previous video and the one we are about to write then the files are located in two async patterns folder so i'll close everything for now and then back in app.js i can remove it like i said if you want to access that code it is sitting in the two async patterns folder and we'll simply start by recreating the read file setup where i'm gonna go with const and i'm right away accessing that from the file system module and i'll set it equal to require of course and then file system all right that's awesome we know that it is asynchronous so we need to set it up with three parameters we go with read file and then we would want to pass in path first so again since i'm in app.js i'm going to be looking for the content and then forward slash and then first txt the file we already created before then we have encoding so comma and then again we're going to go with utf-8 and then last one is going to be that callback where the first value is the error and then the second one is the data that we're getting back okay awesome so once the file system responds then of course we invoke this callback and inside of that callback we have our logic so if there's going to be an error for time being i will just return like so and then if i have the data i'll set it up as else so say here console log and data of course and we shouldn't be surprised if we've seen a console hello this is a first text file because we already covered the setup right so we're passing the path we pass in the encoding and then we set up the callback now the problem starts if we would want to perform multiple actions if i want to read two files and then for example write one correct so what would be a better solution well a better solution would be turning this into a promise and then eventually we'll set up async await now please keep in mind that the only reason why i will type out the promise stuff is because i would want you to understand what is happening behind the scenes but don't worry throughout the course we'll just stick with a sync and a weight syntax and essentially you won't have to worry about what is happening behind the scenes but the first example yes i want you to understand everything in detail so what we could do is create a new function and we can just say const and then i'll call this get text now this get text will take a path since i want to read two files and then eventually write one as well just like we did here and of course the goal here is to showcase how we can make the code in the file fs async at least that's how i called my file much cleaner and more readable so again we pass in the path and then what i would want to return from this function is a promise so we go with return new promise and then in the promise object we need to pass in is another callback function so we pass in the callback function and in here we pass in two more functions one for resolve and then one for reject and then once i have set up both of these parameters now of course what i would want is to move the read file and place it inside of the promised one okay so once we place it here first of all notice here how i'm passing in the path so of course i can change this one around so i can say path and then the encoding stays the same as well as the callback however inside of the callback once i have access to resolve and reject what i could simply say that if there is an error i will spit back the error so say reject an error and if everything goes great now of course let's go with resolve and then we'll pass in the data and once we have this setup what's really cool that now i can invoke get text and this is going to return a promise and then of course we can chain that then and catch so below the get text i can go with get text and of course we're looking for the path so we still would need to use dot and then forward slash and then content of course and first txt so that's the path and then like i said we are returning a promise so we can chain that then and of course here i can have the result and i'll just cancel log it for now or result and then i can also chain that catch and here i'm passing in the error so again we can't log it and we simply would want to see the error i save it and beautiful again in a console i have hello this is first text file so i know that it worked and also if i change the path so if i make my path incorrect we should see in the console the error where of course node cannot find file so if that works now of course we can take a look at how we can make it even cleaner by setting up async 08 and once we have our initial setup once we have turned this into a promise technically we're not out of the woods because if i would want to perform again two file reads and then eventually write the file as well and if i would want to do all of that asynchronously it's still going to be paying just by using the promises so what would be a solution well since we're returning a promise if i use async await i can wait till promise is settled and then decide what i would want to do and the way we set that one up is by creating a new function now please keep one thing in mind where eventually throughout the course those functions that i'm about to set up are going to be provided to us so we'll just attach that async to the callback functions that already provided us by the libraries okay but in this example i'll have to create one from the scratch and again the whole point here is because i would want to create a function a start function that i'm going to set up as a synchronous function and i would want to attach a weight so i would only respond once the promise is settled so in here i go const start and that's my function but i need to set it up right away as async because i would want to use my await keyword correct and then we simply go with const and i know that of course i'm looking for the first file and i'll just say first and that one is equal to get text and basically i want to pass in the same thing here now i do need to place this one in quotation marks so my bad i messed it up a little bit okay i passed it in and that should do it now of course what i'm missing here is a weight so i had this await and now only once the promise is resolved then i'll get my response so what i could do here is just comment these two or you know what this one i cannot comment out yet don't worry we will eventually this one i can comment out and then maybe move this below okay so you don't think that i'm running this code and since i have my function now of course i would need to invoke it so invoke start and check it out now of course i don't have the error which is a good sign i guess and then we'll simply go with log and none first and notice the difference where previously when we were setting up the callbacks we had to nest everything now i'm waiting for this promise to be resolved and only once it's resolved then of course i can do something with the value now every time we have this async await approach what we would want is to wrap this e in the try catch block so if something goes wrong then we have at least a little bit of control over it so i'll set up try catch block and then i'll set up my first await and eventually we'll add here more and then in the error i'll simply go with console.log and we'll console log the error and let's just save that one so now we have nice try and catch block and by the way sorry i deleted it we'll still take a look at the first one and then if we change the path then of course we'll get an error okay so that's good now i have my start function it is the synchronous i'm waiting for the promises to resolve they're all wrapped in try catch block so what's next well if you remember in here what were the actions that we were doing well we read two files correct and then we wrote one okay so let's try that one with this new approach where essentially i have first so just copy and paste and then i'll look for the second file remember we should have that in the content so this is going to be the second one second over here and then i would want to write the file now of course you could say well the problem here is going to be that i'll have to write a new wrapping function to set it up as a promise because yes we can of course read the file but functionality for the write file again we would need to wrap it don't worry there's a way how we can get this actually out of the node first i just want to showcase how much cleaner this already is where i can just wait for first second like so and now notice in the console hello this is the first text and hello this is the second file again i fully understand that you're looking at this wrapper function and you're like well this definitely doesn't look that much cleaner than this one don't worry there's a way for us to get those functions in a way that they're already returning a promise what i would want you to focus on is this code what i would want you to understand that this definitely is much cleaner than what we have here we read the file and then we set up another nested callback and another nested callback and hopefully you get the gist waiting for these promises to resolve is definitely a cleaner and more readable approach all right so this works we have our start function it is asynchronous we're waiting for prompts to resolve and we can see that it is already much cleaner how we can set up this code without the wrapping function well what's really cool that in node there is a module by the name of util and we just go here const and we'll assign it to a variable and we'll just be looking for require of course since we would want to import the module and again the name is util and then instead of this module we have a method by the name of promisify and with the use of this function we can take our read file which of course was looking for the callback and turn it into the function that returns a promise and again this is over simplified version what is happening there but hopefully you understand that as a result we'll get again this promise back now the way we'll set that up of course we have read file here already so i cannot use the same name that's why i'll go with read file and we'll call this promise and that one is equal to util that is of course my module dot and then notice the function promisify and then we pass in that read file function so now i have my promise one so now what i could do is first of all comment this out and move it down again so it stays for your reference but it doesn't compromise my view and of course now i have the error because well get text is not defined that's fine don't worry and i'll copy and paste and since i also want to write a new file i will get from the file system one the right file function and then i'll do the same thing where in this case it's going to be called write file promise and then we pass in write file and of course now instead of calling get text what i'm gonna do is go with right file or i'm sorry in this case we're going for read file promise and then keep in mind one thing where this is not a get text one so we're still looking for the path as well as the encoding that's well copy and paste and then second argument we pass in is the encoding and again our functionality shouldn't change where i should see in console the results from the first txt now of course i want to do the same thing with the second one so have read file promise second txt again we have to pass in the encoding otherwise we'll get the buffer back so copy this and paste and again if we cancel log it there it is we have hello this is first text file and this is the second one and since in the line 4 we passed in write file into promisify of course what we could also do is right away write the file so i can go with await and i'm simply not assigning this to a variable because well i'm getting back on the finder as far as data and i'm just going to go with await write file promise and the same spiel we pass in first the path and in this case of course if the file is not there node will create one and the name will be result and i'll just call this mine grenade and then txt and then the second one is data so for that one i'll set up my template string and i'll just say this is awesome awesome and then let's set up the colon and then we'll access both first as well as the second one so we'll interpolate both of them second and then once we save if we take a look at the content there it is now we have the mind grenade one correct now there's probably one where i was testing yep there's one where i was testing so i'll remove this one but if i take a look at dtxd1 then of course i'll have this is awesome hello this is first text file and then i have the second one now what's even more cool that technically we can even skip this part as well again i'll leave this one for your reference but if you go to require and then you require of course file system module but if you add dot promises what do you think is going to return well effectively the same thing so now of course i just need to change the name from read file promise and write file promise back to read file and write file since those are the two functions that i'm importing and that will right away return promises and again we save and remember that by default we're just overwriting stuff so if i were to go and add a third argument my options one and if i'm just going to say flag and i'll set it equal to upend once we save well now we have this is awesome repeat it one more time again just to showcase that our functionality still works i fully understand that there was a little detour where we created our own wrapper function and then we covered how we would consume promises but hopefully this helps you understand that this approach is definitely way better so it is more readable it is more easier to wrap your head around and that's why for the remainder of the course we'll stick with this one again some things will be provided to us by default so libraries will provide the functions that return promises will right away have the callback functions that we'll just set up as async and hopefully you get the gist so a lot of things will be given to us but the core functionality won't change where instead of using callbacks and nesting them inside of the other callbacks and nesting more and more and more we'll set up everything with async await because the syntax is cleaner and way easier to read excellent once we have covered async patterns we're going to use throughout the course now let's talk about events in node.js when working on browser javascript apps a big part of our work is to handle events for example user clicks a button and of course in our program we handle that user hovers over the link and again same deal in our program we are handling that and hopefully you get the gist essentially as our program executes at least in part it is controlled by events of course depending on a program but it's safe to say that in browser app those events are mostly external now that style of programming is actually called event driven programming and effectively it's just that a style in which the flow of the program is at least in part determined by the events that occur as the program executes now it's easier to imagine that of course when you have a gui right the graphical interface just like the button and links example i just mentioned but what about server side is it also possible and of course the answer is yes in fact event driven programming is used heavily in node.js and in the following videos we'll see some of the examples of it and basically the idea is following we listen for specific events and register functions that will execute in response to those events so once our event takes place callback function fires just like in our imaginary button example now before we continue let me stress something our first examples are going to be basic and even somewhat silly but don't let that fool you many built-in modules in node.js do use events under the hood and therefore making events and event driven programming a big part of nodejs all right and once we have covered general concepts behind events as well as event-driven programming now let's set up our own events in node and the way we do that we come up with a variable and typically this name is event emitter because what we're getting back is the class and we require the events module so require events module and we assign it to a variable which essentially is a class and again a common practice is calling this event emitter and at this point you have two options if you want to create something custom you'll need to extend the class or if you simply want to emit an event as well as listen for it then you can just create the instance so go with the second route we'll go with const and then whatever name you would want in my case i'm just going to call this custom emitter like so and i'll assign it to new emitter so event emitter or however you call this variable and we just need to invoke it so now we have the instance of our class so essentially we have the object now there are many methods in this object however two that we're interested the most are on and emit so on we'll listen for specific amend and then emit of course will emit that event and the way we set it up we go with custom mirror or whatever name you used and then we go with on and at the very basic setup in the on method we just pass in the string where we say the name of the event now in my case i'll name my one response and then of course once i have subscribed to it i also would want to pass in the callback function so essentially when this event takes place well then i would want to do something and in my case i'll just go with console.log and we'll simply say data received or i'll place this one in the template strings and you'll see in a second why so we'll go with data received and then eventually there's going to be some more data and of course once we have subscribed to this specific event now i would want to admit it and the way we do that we just go with custom emitter and of course the method is surprise surprise emit and of course at this point these strings need to match so if i'm emitting the response event and just say here response and what you'll see in the console is wherever you have in callback so of course in my case i have console log data received and then once i run it i have data received in console so that's the most basic setup when it comes to events again we create an instance from the class that we get back from the events module and then we have two methods we have on method as well as the emit method and then in the on method we pass in the string so that's going to be the name of the event as well as the callback function so once this event takes place then of course we would want to do something and in our case we'll just console.log data received and then once we have subscribed to this event then of course we need to emit it and the way we do that we just go with whatever the name is in my case custom emitter then emit method and then we pass in the same string that we're listening for in our case of course response and then the moment we do that we of course have whatever is in the callback function which in of course of course is just a simple log data received all right and once we have covered the basic setup now let me show you some things that i would want you to be aware of first we can have as many methods we would want so for example we have the same event we have here response correct and we are omitting it so nothing stops me here just copy and paste and listen for the same event which of course in our case is this response and then do some other logic in my callback again in my case it's just going to be simple different kinds of log so i'm going to say some other logic here and i'm not going to copy and paste the same function 20 000 times just to prove my point but hopefully understand that yes we can emit our event and then yes also we can have as many functions we would want here that our listening for that event and do some other logic so that's point number one point number two that i would like to make is the fact that this order matters so we first listen for event and then we emit it so for example if i will place my emit above the second function or above both of the functions which you'll notice that i have nothing in a console why well because i first emit the event and only then i listen for it as you can see that doesn't make sense so first we would want to listen for the event and only then we would admit it so in this case notice i don't have this some other logic goes in here because i listen for response and then i right away admit the response and then again i listen for the response but i already admitted the event correct so it doesn't make sense to listen for the event once it has been already emitted so that's the point number two and then thirdly our also on a showcase that we can pass the arguments when we're omitting the event so for example i go here with my emit i pass in the name which is of course response and then i can pass in more arguments for example here i'll go john and then the id number 34. so string and a number and then in my callback function i can access those arguments as parameters just like normal functions so in this case i'll call them name and id and simply in my console.log i'll say name and the second one will be with id and then whatever is that id now i'll add here data received user and then save it and it's no surprise that in the console i see data received user john with id34 now in the second function as you can see i wasn't looking for those arguments i just don't have access to the arguments because i don't have the parameters but it's not like everything broke just because in the event i passed in the arguments and lastly i would just want to reiterate the point that even though you might not write your own events events are a core building block of node and effectively as you're building and writing out the code for your node application you are using those events at the end of the day anyway because a lot of built-in modules rely on them and as a quick side note if you'd like to see the code that we wrote in previous two lectures you can just navigate to 13 event emitter and in order to show that i'll quickly set up a server and again the code for this one you can find at 14 and then request event so copy all the contents from the file and then just copy and paste and notice something interesting where again yes we're getting the http module and remember the setup that we have used so far where we go with http create server and then we pass in this callback function and then of course this callback function will be invoked every time someone visits our server so every time the request comes in now there's another way how we can set it up by using event emitter api so we still create a server we go with http and then create server function but instead of passing in the callback function like we did previously server has the method on does that ring a bell remember our previous example we had our own instance and it had the method of on correct so the same goes for server so server has the method on and we listen for request event and when that request comes in then of course again we have this callback function that handles it so behind the scenes server emits the request event and then of course we can listen for it we can subscribe to it listen for it or respond to it however you'd want to call it and the way we do that we go with server on and then this is a specific name because of course it emits that specific name behind the scene so make sure that it is a request and then the same spiel now how do i know that well if we go to node documentation and if we look for http we keep on scrolling keep on scrolling eventually we'll hit the server and over here i can see that it has a clash okay that's a good start and that what do you see here well i see the event right and what is the event well the name is request so that's how i know that my server the instance that i create has the ability to listen for request events and if you want to dig deeper you can just click on a server you notice that it extends the net server and if we keep on digging check it out so this one extends what it extends the event emitter so hopefully that makes it clear that even though you might not be setting up events on your own a bunch of built-in modules rely heavily on this concept of events all right and up next we have streams in node.js and at its simplest streams are used to read or write sequentially basically when we have to handle and manipulate streaming data for example continuous source or a big file streams come in real handy and now there are four different types of streams we have writable used to write data sequentially then we have readable used to read data sequentially duplex used to both read and write data sequentially and also transform where data can be modified when writing or reading just like with events many built-in modules in node implement streaming interface and what's also interesting streams extend event emitters class which simply means that we can use events like data and and on streams since streams are somewhat off an advanced topic in node i'll try to keep it short and sweet mostly by showing you examples of streams and hopefully that way you get the main idea without being overwhelmed all right and once we know the theory behind the streams now let's take a look at the practical example and a very good use case is using streams when we are reading files because we need to understand one thing where when we use the sync or asynchronous approach what happens we're reading the whole file and of course in our example we were setting this equal to a variable correct but if we have a big file well first of all you're just using all that memory and second as the file size gets bigger and bigger bigger eventually the variable is not going to be good enough you will get an error that i mean the size is too big and you cannot place everything in the string so what would be a solution one solution would be read stream option and the way we'll set this up i'm going to start app.js from scratch but if you take a look at the repo you'll notice this 15 create big file so previously when we were working with files i just had some small files right so i had the first txt blah blah blah result and whatever now before we set up the read stream i would want to create a big file again this is optional you don't have to do that but in my case in order to show you how the streams work yes i'll have to set up a big file and first i'll remove it because of course i already have it since i was testing it and now i'll stop my server and of course in my case i'll run 15 the create big file js if you want to set it on your own and if you don't want to use the repo you can just get the right file sync from the fs module and then notice i have the loop where i believe i have here 10 000 and then every iteration i just write a big txt i of course i have the flag upend and then i'm just adding hello world and starting a new line so if i'll run node and then of course i'm going to go with my file name which is 15 then hyphen create big file and js like so then in the content i should have this big file and once i have my big file i'll go back to app.js and i'll use my npm start since of course i have known mine in place and then let's go with cons now i'm not going to show you how the setup would look like with file sync or the asynchronous one again hopefully you understand that the setup would be exactly the same like we have in 10 and 11 where we had the fa sync and fa async and now of course let's just go with the stream option so the method name is create read stream and we require that from the fs module like so and then we create a new variable and in my case i'll call this stream and we invoke the create read stream and the only thing by default we need to pass in is the path so of course in my case i'm going to go with content and then forward slash and since i just created that text file the big one of course i'm going to go with big txt and now remember the good old friends events well once we create this instance we actually have access to them and the ones that we're going to use is going to be data and error so we can go with stream and then on and remember the event syntax and then the event that you would want to listen for is a data and then we have our callback function and again it is a parameter so we can call whatever we would want but in my case i'm going to go result and let's just console.log the result like so and what you'll notice is that we have 64 kilobytes here that's our first console log then we have another one 464 kilobytes and the reason why i know that is because by default that's the size we're getting and then we're getting the reminder now just to prove my point i'm going to go to my folder and i'm going to look for my content and then in there if you take a look the big text file we created is 169 kilobytes so as you can see now we're reading data in chunks and by default that chunk is 64 kilobytes and every time we cancel log we see that we have 64 64 and eventually we have the remainder so instead of reading everything and placing that in the variable we're doing that in chunks and as you can see we're using the event and the event is data and in order to hammer this home why don't we take a look at the docs so first i'm going to look for my file system and then let's look for our create read stream so we go here as we can see we have this class read stream and then on this class we have these three ones we have close open and ready and as a side note we'll use this one a little bit later as well the open one so keep an eye on this one and then as far as the read stream well as you can see it is created when we go with create read stream and invoke it right so i got the create read stream that's my function i just passed in the past and i invoked it and in turn that returns the read stream right then actual read stream extends from stream.readable so right away i have these events i have close open and ready and like i said we use this open a little bit later now since it is extending from the stream check it out now of course i have the data one all right so this is a chunk of data and as you can see every time we are getting that data we can do something with it now at the moment we're just going to logging it's very simple but eventually as you can already imagine we can do way more useful things than that beautiful once we understand the basics now let's take a look at some additional info like i said by default the size of the buffer is going to be 64 kilobytes however we can also control it and the way we do that is by passing in the object when we're setting up create read stream so first argument is going to be the path which again in my case is going to be that big text file that i created using my file using my for loop and then i can pass in the options object and in there the property that you're looking for the property that controls the size of the buffer has the name of high water mark so for example if i go with 90 000 here then of course you'll see that i'll have two console logs one for 90 kilobytes and the second one will be remainder again keep in mind that our file size is 169 kilobytes that's number one number two we can right away set up the encoding as well so i go with comma and then the property name is encoding and again we'll set it up equal to utf-8 like so and then you'll see in a console of course the hello world why well because that is the content coming from the file and lastly i also would want to mention that we have the error event as well so if i go with stream and then on and we're checking for the error and as always we can do something once that error happens so that's our callback function and in this case i'll just access the error property and i'll console.log the error so i'll say here error and the way we check that one out is by providing wrong path so in my case i'm just going to add two dots and then once i save check it out in a console i'll have the error where it tells me that no such file or directory all right and now let's take a look at the practical example when streams come in handy now again this is going to be one of those videos where you don't have to code along you can just sit back and relax and see how i struggle and first what i want is to make it even a bigger file so remember d15 create big file i believe i had 10 iterations right so i'm gonna add one more meaning i'll add one more zero i'll stop my server right now again this is optional you don't have to do that and i'll remove the big file like so and then i'll run one more time the file with node and then of course this file is going to be way bigger so let me navigate to my folder just to showcase that and i'm looking for content and now the big file is 1.8 megs now once i have the big file i'll go with npm start at the moment i just have the stream example but if you want to see the whole code just take a look at the file number 17 and notice again we're creating a http server and i'm just using the read file stick method i'm looking for big txt the encoding is utf-8 and then i just place my variable my text one into res dot and method and effectively i'm just sending my big text file and let me restart the server here so let me go with npm start right now so let me select everything from this file and copy and paste and now if we navigate to localhost 5000 we should see a bunch of hello world now the problem with the setup is following where if i go to developer tools and if i take a look at the network and if i refresh yep this request was successful take a look at the size do you think it is the smartest thing to send these type of files over the wire and of course this is just going to make it very difficult to all your users because you're just sending large chunks of data effectively i'm sending the whole file and more specifically if i click check it out so i have the request url okay that is good the method is get now as you can see the content length is my 1.8 megs right and you'll see in a second that once we refactor this to read stream method that we're sending data in the chunks and again the best way to see that is by looking at the headers where at the moment i can see the content length and that one is at 1.8 megs but once we refactor that the setup is going to be different so at the moment i have this text i'm accessing that by read file sync so comment this out and let's set it up with our create read stream so i'll go with const and i'll call this file stream and this is going to be equal to fs and then create read stream now use the same address so use the same path and then i'll use the same encoding as well so let's go with utf-8 okay awesome and once we set up the stream remember we have access to to events file stream on and of course i'm going to be looking for the open and i'll have my callback function and we'll set that functionality up in a second and the second one of course is the error so go with file stream and then on and again we're looking for the event by the name of error and then in our callback function we can access the error and i'll simply pass it in in my response so if there is an error i'll just grab the error from my parameter and pass it in now as far as the open here instead of setting it equal to instead of going res dot end and then text file stream also have the pipe method so we can go to file stream and then pipe and what the pipe is doing it is pushing from the read stream into right stream so you can imagine that if we can read data in chunks we can also write data in chunks and what happens under the herd response object can be set up as a writable stream so we have our file stream so that's our read stream we have method of pipe so we're piping this into a writable stream and now of course i'll pass in my response object and if we go back to the browser and if we'll refresh now notice something interesting yeah still same request right to localhost 5000 still same size but if i take a look at the headers now i can see that my response headers are chunked so instead of sending our file back in one large instance we're sending it back in chunks awesome congrats on completing section number three node fundamentals and hopefully after watching the section you have a good general understanding of how node works and now that we're big shots let's apply that knowledge and build some servers shall we and we're going to start section 4 with the general info of how the web works more specifically how we exchange data on the web and we're going to do that with the help of few slides now if you're one of the people who's already reached a daily slide limit i hear you once we're done with these suckers i promise we'll mostly actually write code for the remainder of the course i do believe though that before we build an actual web server it's crucial for us to understand how it works under the hood and that way we'll have clear understanding of what tasks need to be done if something is iffy you can always go back to the slides you already know where they're located and also as we're going to be progressing with the course from time to time i will swing back to them when i'll need to emphasize a specific point with that said let's talk about how we exchange data on the web um it's safe to say that if you're watching this video you know how to use a web browser but under the hood the way it works every time we open up a browser and we type the url so the web address we're actually performing a request and we are performing a request to the server that is responsible serving those resources so for example when you look for cnn.com you're looking for a server that has those resources and then that server sends you back the response and the same works with youtube the same works with johnsmeld.com or whatever so you just pick a resource you say hey can i get this data and then server who is responsible for those resources just sends you back the response now that is done using http protocol and that's why these ones are called http messages so the user sends the http request message and then the server sends the http response message and that's how we exchange data on web and for the remainder of the course we'll be responsible for building such web server using node and more specifically express now i'll talk about it while we use express as well show you a few examples later on in a course but for now just remember that yes we'll use node but in order to make our lives easier we'll use the framework by the name of express js and lastly i would just want to mention that even though name server definitely sounds way cooler than the computer at the end of the day they're just computers whose job is to always make that resource available so yes those are computers and yes there are some differences for example they most likely don't have the graphical interface or the gui and also they're probably much bigger than your laptop but at the end of the day they are computers whose job is to always make sure that that resource is available because imagine if you would have a server that only works from eight to five so if you go to your website at i don't know six o'clock at night you cannot access the resource probably that's not the service that you would pick so next time when someone asks you if it rains does the cloud still work you know what to answer because at the end of the day when we talk about cloud cloud is just a bunch of these servers bunch of these computers connected together beautiful and once we have a general understanding how data is exchanged on a web let's also cover how http messages are structured please keep in mind that since it's going to be a big part of our job we'll come back to this particular slide more than once so if you're if you're about something just please be patient and i'll answer all of your questions as we move along with the course with that said the general structure for both messages is similar they both have a start line they both have optional headers a blank line that indicates that all the meta info has been sent and effectively headers are that meta info as well as optional body and before we continue again let me stress something so request messages are what the user is sending so for example if you open up the browser to search the web or that could be your web application because remember with web applications we also can make http requests correct and then response is going to be our responsibility so we'll have to set up a proper server that sends a correct response and in general when we talk about the request message in start line there's going to be a method then the url as well as the http version now we are mostly going to be interested in these two things in the method as well as the url now there's going to be a separate slide about the methods as well and don't worry we'll cover that in a greater detail once we cover them with actual code examples so i'll come back to that slide just understand the general idea that when we talk about methods effectively we're communicating what we would want to do so for example if i want to get the resource i'm going to set it up as a get request now if i want to add the resource then of course this is going to be a post request and then of course you can read the rest now why i'm displaying here this get because that is the default request that the browser performs since when we open up the browser we want to get some kind of resource correct that's why we're performing a get request and the url is just the address and that could be for example johnsmilk.com or that could be i don't know espn forward slash basketball both of them are just a web addresses now headers is essentially optional where this is a meta information about our request and just to give you a general idea how the headers would look like they would look something like this so it is a key value pairs now don't freak out as you know when you search the web you don't need to add them manually and the same is going to be with our server a lot of it is going to be taken care of but yes some things we'll have to add on our own basically this is going to be information about our message and then we also have optional body so when the user is requesting something if you just want the resource there is nobody there's nothing basically what to send however if we would want to add a resource onto the server yes then you are expected to provide that data and it's also called payload so again i might use them interchangeably so that's the general structure of the request message we have the start line we have the headers that is the information about our message as well as the black line which just indicates that we're done with the meta information and optional body which we'll use from time to time and now of course we need to talk about the response message so response message is what we're going to be creating again most of it will be done for us but some parts yes we'll have to do it manually and it's going to be our responsibility so the start line has the http version which most likely is going to be 1.1 then we have a status code and status text now when it comes to status code it just signals what is the result of the request so for example notice here this 200 that means that request was successful so that's what we're sending back and yes there's quite a few of those codes and as we move along with the course of course we will cover them but please please please don't rush over to the search engine and start memorizing the status codes pretty much as we're going to be building the application i'll tell you which code means what and for example 400 means that there was some kind of request error so the user was trying to request some kind of research and with 400 there was a request error now for example the code 404 means that the resource is not found so when i'm sending back the message i'm like hey listen here's the status code for the message if you are successful here's 200 if there was an error for example you get a 400 if the request is unauthorized then you can get 401 and hopefully you get the gist and yes of course as we're progressing we will cover more status code then again we have the headers where basically we provide info about our message our response message and again like i said you won't have to type everything line by line but effectively it is a setup of key value pairs and the ones that i would like to mention are these ones notice this content type we have text html that is when we're sending back the html but also our second option is going to be sending back the data so hopefully you are aware that when you're building a web application when we communicate with api most of the time we're getting back the json data because over the web effectively we just send over the string so if for example i have some kind of array we transfer this into application json and i clearly indicate that in my headers where i say that no i'm not sending text and html i'm actually sending a application json and then that application who is requesting the web application knows that hey from the server i'm getting a content type which is application json so for example in that case i could send back here this array with bunch of these objects and just to give you a real-world taste why don't we do this open up a new browser tab and i'm simply going to course api because i think there's going to be less data so there's going to be less clutter so go to course api here and then you can either pick the slides or you can just look at the home page and if you inspect and if you look in the browser tab you'll find a network and very useful one is this one where we can just look for all the requests we refresh and then check it out so these are the requests that browser performed and i'll talk about it a bit later why there's also this style css in fact that's going to be one of our first examples but take a look at this one so i have this course api and then forward slash and if you remember when we were building our original server what i said that if we have this forward slash that just means home page so if we're just navigating to courseapi.com and that is our homepage we simply add this forward slash now of course in the browser that's automatically added but that's why when we're setting up the server one of the cases is going to be if the user navigates to the homepage then we simply look for forward slash so if for example you go to the slides you'll notice that uh in this case i would have to refresh notice here i have the course api forward slash slides so that is already a page in my website correct so i have the home page course api and then i have the slides page where i have the slides and if you take a look if you click on it notice all the useful data that we get over here so for example this is going to be our request url which is going to be again course api.com so that tells me well what the browser is trying to get then check it out the method why it's get because that is default in the browsers every time you open up the browser and search something then of course you'll be performing a get request now check out this one the status code it is 200 why because everything is successful because servers send back the data then we have this remote address and basically that is the ip address for my server as well as notice this colon 443 and we'll come back to this one when we set up our own server because if you remember we were always setting up the 5000 so you're probably wondering well what is this 443 and don't worry again we'll cover that one once we set up our first server and then again we have response headers for example and we also have the request adders so as you can see using this network tab we can actually find a bunch of useful information now notice here in the second set of tabs i can see this response and preview so if you take a look at the preview this is going to be basically my site and also i can see the response so as you can see pretty much sending back the html so i'm sending back the website so you go into the browser you request a resource by default it is a get request and then in that body when the server sends it back this is what we get back so we get back the site so hopefully this gives you a clear understanding of how the http messages are structured and now let's dive into creating our own server awesome once we're done with the slides now let's start setting up our server and in order to follow along with the course you'll need to have a starter project and you can get it if you navigate to my site again the url is johnsmilk.com so navigate there in the project or in home page look for node express tutorial project in a home page is going to be at the bottom in latest project if you cannot find it there then look for all projects page or simply projects page then filter for node in order to save some time and then like i already previously mentioned any of these links will get you to the repo and then bravely get the repo in my case i'm going to clone it so i'll copy the url i'll bump up the sound size in my terminal navigate to the desktop get clone here and then i'm gonna get the repo and then once the project is on my machine i'm just gonna drag and drop and then the first thing that i would suggest doing is removing the remote url and you can simply do that by just wiping out the git folder so that way if you ever do decide you push this up to the github you won't have some dumb permission errors so i'm just going to open up the integrated terminal now in my case i'm not going to run the command but if you're on mac i suggest running rm then hyphen rf and then get now if you are on windows some students have just these two commands now i haven't tested them yet but some people have replied to my tweet that yes they do work and if you want to see the whole tweet just navigate to my twitter the handle is john underscore smilga and then as you can see here is the mac command and for windows i have these two so run this command and then in next video i'll give you a brief overview of the repo all right and before we get busy why don't i give you a brief overview of the ripple and if you take a look at the first project this should look very very familiar because essentially this is all the code we have written so far everything starting with our most basic application and then of course we also have our last one our http streams example so hopefully that is clear and if you ever need to jog your memory essentially this is just here for your reference and then from now on we'll work in a folder number two by the name of express tutorial and the idea is gonna be exactly the same where basically we build a bunch of examples and in the process we learned what is express and why we would prefer using express instead of straight up http module but again let me stress something where express is built on top of node and more specifically on top of http module so it's not like you can use express without node and in folder two the setup is following where there are gonna be some assets that i provided just so we can make more real world examples so hopefully that gives you a better idea how the express works and i'm not going to cover them right now for example methods public or navbar app once we get there i'll explain everything that's happening i think that it's going to be waste of our time if i do that right now however if you take a look at the final folder you'll basically see all our examples so the same spiel if you ever need to reference the code just navigate to the final look for the file name and then of course you'll find the code just keep in mind that in order to run this code you'll have to copy and paste and run it in the app.js why because in some cases there's going to be paths and since these files are located already in the final the paths won't match okay hopefully that one is clear as well and then we also should be familiar with these files as you can see i have package.json i have package.json lock and then app.js now of course app.js could be renamed server or whatever you would want but i already have in a package.json a script that spins up the nodemon and effectively we have successfully set up a node application so package.json is of course needed because we'll have some dependencies more specifically two one is going to be nodemod and the second one is going to be express and in order to of course keep track of those dependencies we have package.json and then if you notice i don't have the node modules here and of course the reason for that is because i don't want this repo to be massive and you can clearly see that in a git ignore where i have node modules included so when i was pushing this up to the github and of course i omitted the node modules since i added them in the git ignore and then in the package json like i said you'll find some dependencies and i'll talk about express once we get there the moment let's not worry about it the one that we should be familiar with is node one which is going to be watching our application and i have a script that sets up nodemon and passes in the amp.js so any changes in our project nodemon will be watching and restarting our application however we cannot do anything before we install all dependencies otherwise you'll just get an error so that's why the first thing that i would want you to do is navigate to the folder number two and the fastest way probably is just going to be cd and then take the project number two and drag and drop like so and then once you can see that you are in this folder so not in a root not in node express course but once you are actually in the folder number two before you do anything just run npm install first and then it's really up to you you can either wait for all the dependencies to be installed and then run npm start or you can simply chain it and say npm and once you run this one then of course you'll install dependencies and if you see in a terminal express tutorial that means that everything is correct and you can continue with the videos if you don't see that then please troubleshoot because none of the things that we're about to do next are going to make sense if you're not running the project number two with all the dependencies more specifically nodemon and express and lastly i just want to mention yes there's also this data.js and again this is one of the assets that i added that we're going to use a little bit later so if you see express tutorial in a console and the reason why it's there because that's the only line of code i have in my app.js that means that everything is correct and we can move on to our next topic and why don't we start the express tutorial part by setting up the server one more time with straight up http module and in a process let's struggle a little bit let's see why we would want to use express e in the first place so yes we'll build one more time server with http module however now of course we'll dive deep into the topics that we kind of skipped over before and in order to set up the server we know that we would need to require the module right so i'm going to come up with some kind of variable and in my case that is going to be http and of course the name is not required you can call this whatever you'd want but it is somewhat off a convention to call this hdp as far as the variable name then we go with require and we just go with http again keep in mind this comes built in node so you don't have to install it we didn't install when we ran npm installed in last video we installed two other dependencies but this one is built in so we don't have to do anything we just say require and it's always going to be available to us then we need to set up the server and again convention is calling the server but you can call this box bunny and in order to do that we go with http and then on this object we have a method by the name of create server now this method takes a callback which is going to be invoked every time the user hits our server and in this callback we have two parameters and again we can call them whatever we would want so again common convention is just shorten this up a little bit and call it request and res so rec and res and the first parameter references the request object and second one is the response object and at this point it should be clear why we have access to those two parameters because in the http cycle we have request message that is coming in every time user requests the resource and also we have the response message right so that's what we need to send out so that's why in this function that runs every time user hits the server we have access to rec and res so that way we can find info about the incoming request because it makes a total sense if we have access to that info i do want to know what is the method so what the user is trying to do i do want to know what resource the user is trying to get whether that is the contact page or about page and also i would want to know whether i'm getting some data whether user is trying to add something onto the server and as far as the response well in order to serve the data i need to be extremely specific about what i'm sending so i need to explain to the browser what is coming in hopefully that is clear and in here we can just go with log and we'll say user hit the server and then we return the object from this create server and on that object we have a method by the name of listen so in order for the server to work we need to invoke listen and we need to be a bit more specific and we need to say well what port are we listening for and you're probably wondering well what's up with this port what's up with this 5000 value and the best explanation i can give you is this one imagine scenario where you have some kind of issue with your bank what do you do or that could be a phone company it doesn't really matter but i'm just going to give you a bank example what do you do you call the customer service and what is the first question that they ask you they say please describe your issue so we may better assist with your call and what do they do they give you options right so they say if you want to increase your credit limit this is going to be option number one all the way to canceling the account which maybe is going to be option number eight so they don't just randomly assist you a person they say hey what is the issue and this is the person that can serve you the best so if you press 8 you can assume that you're probably going to be speaking with someone who deals with that all the time and same goes here so if you go online and if you search for port this is just going to be a communication endpoint and we need to understand that for http traffic we have specific ports so for http we actually have port 80 because there's other ports as well if you keep on scrolling here and by the way this is wikipedia example we have port 20 which is for file transfer protocol so this is going to be for data transfer then we have port 22 for secure shell so http traffic is only one of the things that we set up on a server and once our application is in deployment we have specific ports for that we have 80 that is going to be for just http and we also have 443 which is going to be 40 secure communication that's why when you go to course api or any other website that uses https you'll notice that there is a ip address and then more specifically 443 and you can also think of this as a apartment building so every apartment building has the same exact address right but the apartments differ so the same works here so on that server if i want to access it using ssh so secure shell i'm going to use port 22 but then if for example i want to use http protocol and if i want to access resource that way then i'm going to use port 443 so once your server is already in production yes these ports are not random there are specific ports for specific things we would want to do again back to our bank example if i want to cancel the account then i'm always going to be directed to that person because i'm going to click option number eight if i want to increase the limit then of course i'm going to be directed to a different person now while we're in development this is really arbitrary i can go here with five thousand i can go here with three thousand eight thousand wherever you would want i believe the ports between zero and thousand twenty four are already taken so you shouldn't be using them but in local development again this is an arbitrary number and that's why you can use anything you would want and again the most common example create react app where we spin up the server on localhost 3000 then gatsby has i believe eight thousand and then netlify cli has 8080 and i can go on and on and on so in my case i just went with 5000 but if you don't like this number just use a different port but of course please remember the actual value for the port because you'll need it once you need to access now if you're wondering well what happens once we deploy our application just put the pin on that and once we get to deployment of course i'm going to cover how actually we set it up that we serve that traffic on the port 80 for example for http or 443 for https and now of course we can go and test it out so let me navigate to my browser and i'm just going to go with localhost and eight thousand and or i'm sorry i just said five thousand and for some reason i went to eight which is gonna be the gatsby one and you'll see this interesting spinner so what's happening over here well the thing is yeah the user hit the server as you can see user hit the server that is what i see in the terminal however remember we have the response right so we have access to the response object and now we need to send back some info to the browser otherwise the browser is like okay so i hit this resource but nothing is happening and there's a method that we always always need to include in our response and the method name is and and i right away went to node docs of course again if you want to navigate there yourself please do so but i already right away went for response dot end and as you can see this method signals to the server that all the response headers and body have been sent and as a side note we'll do the headers in the next video because this one is already getting quite long that server should consider this message complete the method response and must be called on each response so for the browser not to be confused we need to go with res that end so res dot and that is one of the methods that is available on this response object and here we can either pass the text or we can set up for example html and in this case i'm just going to say home page that's it i'll just pass in the string and if we were to go back to localhost 5000 there it is now we have our homepage response and we can clearly see that in our terminal because every time you refresh the browser you'll have this console log in a terminal user hit the service hopefully everything is clear again we have access to http module and that is built in node and we just set it up some kind of variable most common convention is calling this http then on there we have create server method that takes in the callback which is going to be invoked every time the user hits the server and as parameters we have a request and response object and common convention is just calling the american res now of course you can call this stockhold burrito if you want but again common convention is calling this iraq and res and the reason why we have access to those objects is because in the http cycle that's what happens we have a request message that is coming in where we can find a bunch of useful info about the request that is coming in and then of course we need to respond to the browser in a meaningful manner so that's why we also have the response object and in every response we should always have end which is going to signal that the communication is over and then we just need to set up the port and again in development we just come up with arbitrary numbers and in my case we go with 5000 and we pass in that port in the dot listen method which is available when we invoke create server because we get back the object hopefully the basics are clear and now we can start expanding on our knowledge all right we're done with the basics but there are two major issues with our current setup first of all we don't provide any info about the data that we're sending back so we don't have any metadata about the body that we're sending out so we're not providing any information we just go rest that end and then pass in the string so that's issue number one and then issue number two if i were to go to the local host 5000 and if i type about or if i type contact or whatever you'll see that of course we're sending back the same response each and every time so if we go with contact again this is going to be a home page so why don't we deal with issue number one first where we provide more info to the browser of what we're actually sending back and then in the next video we'll deal with the request and the way we provide more info we just need to add more methods now specifically one more method and that is going to be res dot write head and in there you can probably already guess that we're just providing headers so we're providing metadata about our response and we go here with res dot and then we go with right head so right head and then we need to provide a few things we start with a status code and i'll talk about the status code in a second and for time being i'll just pass in 200 which just means that the request was successful and then we pass in the headers and one of the most common headers is the content type so this is where i specifically say to the browser hey listen i'm sending back html or i'm sending back css so where i'm sending back the image so browser knows well what to do how to render that content and like i mentioned already previously this is done using key value pairs so we go with content type so that's the name of the header and then we pass in text and then if for example i want to pass in the html i go with text forward slash and then html and now of course in this case where i have the res.end i can set up the html so for example i could go with heading 1 and i'll say homepage same deal home page now if you want you can keep it this way where you have res that end and you directly pass in the html however i like to use better this approach where i go with res dot write and we do the same thing we pass in essentially the body and i set up my html here in the right or any content that i'm sending back and then explicitly call res.n again if you want you can pass this heading 1 into the end just make sure that you have the end and you saw that in a docs where it says if data is specified in a similar effect to calling response.write and then we pass in the data followed by res.n but you always always need to call res.n so this is really up to you if you want you can pass this directly into res.n i like to write it a bit explicitly where i say res.right so that is my body and then i just end the communication by calling res.n and now of course if i go back to the browser again i'll still have the same issue where it's going to be displayed for every request meaning either contact page homepage or whatever but now i provide way more useful info to the browser where browser knows hey i'm getting back the html so i'll need to render html and this stuff matters so let me show you if i change the content type back for example to plain and if i save and if you refresh now notice this is now treated as a text it's not treated as html so whatever you set up over here in the content type yes it does matter now express takes care of that so we won't have to do that but i just want to let you know that if you will be setting up the headers yourself yes the stuff that you type here matters and as the note it is also called mime type or you can think of it as media type so whatever we're sending back and now let's go over the status codes as well as other options for mime types and this is where i would like to introduce an awesome resource for anything http related and that is going to be no other than the mozilla docs so if you go to http and status codes you'll see probably the first link is going to be to the mdn and as you can see http response status codes indicate whether specific http request has been successfully completed and like i mentioned before there are quite a few groups over here and there are quite a few codes but i would strongly discourage you from spending your weekend on memorizing the codes as we're going to be progressing with the course as we're going to be creating more complex applications of course we'll introduce more and more status codes but the main idea is following where when we send back the response i'm just saying is it successful maybe the resource wasn't available so then i sent back 404 or maybe there was a bad request that's why there's also option 400 and hopefully you get an idea where we are setting up that status code so the browser knows what is happening with the request was it successful was there an error maybe i don't know you're not authorized to access it and on and on and on and if you keep on scrolling notice so the 100 ones are going to be informational responses then for successful one we have 200 so that probably is going to be the one that you'll use the most so that means that request has succeeded then we have 201 also something that we'll use throughout the course a lot and this one is once the post request is successful so if you add the resource successfully onto the server then you just send back to one we have 300s for redirect and then these are the ones that you probably don't want to get if you are surfing the web so 400 is for bad requests so for example you are requesting some kind of data or you're trying to do something on the server but you don't provide the info so i don't know i'm trying to add the user but i don't provide the username something along those lines then 401 is for unauthorized then 403 forbidden and 404 not found so in our case we'll set up a response if the user is trying to access the resource that does not exist so hopefully it is clear that is the status code again i wouldn't suggest memorizing it as we are moving along with the course of course we'll cover more status codes just understand the main idea where you attach that status code to let the browser know hey what's happening and it is very important that you use the correct status codes because we are in charge here nothing stops me from sending back the 404 here meaning the resource is not found and then when you navigate to the contact page for example here and if you inspect again the browser network tab you'll see this confusion info where 404 is technically not found right but at the same time we are sending back the correct resource so yes whatever we type as far as the status code it does matter it's not just some random info and that just reflects what is happening with the request and then lastly let's talk about mime types same deal just go to your favorite search engine and just type mime and types and again i suggest using the mdn and these are just going to be media types so whatever we're sending back there's quite a few out there now again express takes care of that so we don't need to worry about it but if you ever need to set it up i don't suggest memorizing them the ones that you'll need to use you'll pretty much be able to google it right away you can also use the npm packages so no you don't need to go and memorize them again just remember the main idea where you're sending back something right and you need to describe to the browser well what are you sending back are you sending back the image are you sending back css are you sending back the html and as you saw in a previous example if you change that mime type if you change that content type header yes the browser will interpret that differently and once we successfully have set up more proper response now let's start dealing with the request object beautiful and with our basic headers in place now let's deal with the request object and like i already previously mentioned it's just a giant object and if of course we can slog it then we'll see it in a terminal so i'm going to go back to my localhost 5000 and as i said note this is getting quite busy so i can just remove some of the tabs and if i just refresh the browser i should see in a terminal a giant object so what are we looking for well let's go back to our slide and remember the start line we had a method so that signals what the user is trying to do either get the resource post a resource or whatever and then we have the url now in order to save us a little bit of time i won't cover the methods with http we'll just deal with the url but we will cover of course methods once we hit the express for now i'm just going to assume that the only thing that the users are trying to do they just want to get the resources from our server so that's why we won't look for the method just keep in mind that yes of course those methods are available on this request object there is a property by the name of i believe it was just simply a method so if we cancel log and if i refresh notice here in a terminal it says get so the user is performing a get request so the user is trying to get the resource so that's one thing that we could take a look at and the other one is actually the url so let me uncomment this one and i'm looking for the url property and again i refresh and now in the console i should have this forward slash contact so that just means that the user is trying to access the resource by the name of contact and if of course the resource is there awesome we send something back if not then most likely would send back the 404 now if i delete that contact and if i simply go with 5000 notice i'm going to have the forward slash so again this just signals that we're getting the home page so forward slash is going to be the home page and then whatever other resource we would want we would have port slash and then the resource now sometimes those resources are going to be forward slash resource name and then another forward slash and another resource name and on and on and on you can really type here whatever you want so again i go with localhost about and then info and i don't know something john right so i can add that here and there it is now i'm requesting this resource and if it's not there we send back 404 if it's there then of course we send back the useful info so hopefully that is clear yes this will just mean that it is a homepage and whatever comes after the homepage well that's the resource that the user is trying to access and now of course we can set up the if statement whereas say yes if it is a home page please send back this html if it is about page then send something else and then if i cannot find that resource that you're looking for then we'll send back 404. now there's going to be a little bit of copy and pasting just so we can save a little bit of time we're just going to go with if and actually we can set this up as a property so let's go to const url is equal to request url and then we'll say if url is equal to forward slash what does that mean well that means that it is a homepage so let's grab these three lines of code and move them up and now of course i want to set up else if now i'll just set up one for the about page so if url is equal to about page then we'll do something else and if none of those match well then i'll just say else and i'll send back 404 now i will add some comments here just so we are clear on what is happening so this is going to be about page then this is going to be called home page home page and then we're going to have the 404 so resource not found so again in order to save us a little bit of time let's just copy and paste one and two and again content type will be exactly the same so that is going to be html because we'll send back the html i'll say about and i don't know page let's call that and then last one is going to be the 404 so in here of course we're not going to send back 200. 200 is for successful request now of course i want to say hey listen the resource that you're trying to access well it doesn't exist on my server so here i go with 404 and again i go with the same content type text html and then let's just send back the heading 1 with page not found so save this one and now of course once i refresh check it out i get this page not found why well because there is no resource forward slash about info and john but if i go to just about there it is now of course i have my about page and then if i go back to the homepage of course i have heading 1 with a home page now we optionally if we want we can add the status text as well and in order to see that let's just go back to the node docs so this is going to be the http and of course i'm looking for right head and we have a right head here notice we have status code optionally we can pass in status message and then we have the headers so again let's go back to our slide this is the most important one status code and then the status text essentially is just going to be added in this case we don't need to do anything because again if we were to go back to the browser network tab and if we take a look at our localhost there is first of all this is forward slash that just means that we're going to the homepage and the status code is 200 and then we have this status text now again if i navigate to a page that doesn't exist for example john then of course i'm going to get the 404 so that's the status code and then the status text is not found so hopefully it is clear now we have a bit more meaningful server where we have multiple resources we have home page we have the about page and also we have the error page and with this in place now of course we can start working on more complex setup nice and with our most basic example in place now i'm going to start throwing mine grenades at you first of all i want to let you know that of course we're not limited to passing in the html directly into the dot right or that end meaning imagine if you would have to every time just set it up or your html in methods directly of course what we can do instead is set up the file then require the file using the file system and then just pass it in now keep in mind one thing though where we will be passing in the contents of the file not the file itself and that's very important we'll be passing in the contents of the file so that means we still need to use this content type just because we're going to be getting the data from the html file doesn't really mean anything yes it's nice it's going to make our lives easier if you want to set up a more meaningful web page but we still need to set up the content type now this is going to be a temporary file because in the next video we'll cover a more serious example and i already prepared all the files for you so this is where we'll really struggle and this is where i'll show you why we use the express but for now if you want to follow along just create a simple index html or about html doesn't really matter how you call the file in the folder again this is really optional i'm going to go with new file and i'm gonna call this index html and again the whole reason why i'm doing that because i wanna set up a more proper page and i don't wanna type everything here in the right or end i mean it's much more nicer here right so i'm just going to go with emma setup in visual studio code i get my basics and i can say home page home page and then i'm just going to go with a heading 4 of hello world again this is just a showcase that sky is the limit just like you normally would set up to html you can do exactly the same thing and then i'm going to go back to app.js and first of all i'm going to get the read file so i'm gonna go with const and then read file and sync and i'm gonna talk about why i'm using this thing in a second so don't freak out i know i mentioned before that we need to be mindful of the methods that we use that there is a difference between the blocking and non-blocking and i'm just going to go with fs over here and we need to come up with some kind of name and again in the next video there's going to be more data here so that's why i'll say get all files for time being in this video i'll just get one and i'm going to call this home page again call it whatever you would want you can call this bobby lee doesn't really matter it's just a variable and we're going to go with read file and sync and of course where's the file it is in the same folder so we go with relative path and i'm just going to call this index html now again we're getting the contents now why i'm using here they read file sync well there's two reasons first of all we need to keep in mind that we're not invoking this every time someone comes to the server please keep in mind that we require that file when we instantiate our server so basically that initial time when the server starts running so it's not like when the request comes in then again every time we're requesting the file yes of course if i were to place this in the if block yeah that's a different scenario meaning if i were to even place this in a create server again same scenario but not in here again we're just requesting this once that's the first reason why i went with that and second it's just an example so i want to make my life a little bit easier what i want to focus on is something else with this home page in place now of course what i would want is to go back to my if where i'm checking for the homepage and instead of going with res.right and then typing it out i'm just going to go with our content now again we're still keeping this one the text.html and i'll show you in a second what happens if we change it to a text plane and now we go with a homepage and now be prepared to be amazed because if i go to not john my resource of course doesn't exist there it is check it out we have home page as well as the hello world so we can start making some meaningful html pages and we can serve them with our awesome server and just to re-emphasize my point if we change this to a plane and save and refresh now of course we're getting a text so yes it is very important of what content type we are setting up so let's go back to html and now of course we are in good shape awesome we have our homepage and now of course i can go to index.html and go wild and crazy with my page setup not bad not bad now we know that we can access the contents of the file directly so of course we can set up proper pages but now let me throw you a mine grenade where we'll have to add way more code here if we want to really serve some meaningful web page and the example is going to be following if you navigate to navbar app so that's the folder you'll find index.html you'll find style css logo svg as well as browser hyphen app.js and i simply call this browser app file so you're not confused between the two so this is going to be for our server and this is our browser app and effectively this is a complete app that we set up i believe in my javascript course when we were building projects so effectively this is a little navbar with a toggle functionality and let me assure you something right from the get go the app works so if you get any issues along the way it's because the node is not working the app itself is going to work and i can simply showcase that if i go to navbar app and i'm going to copy that one and i'll place it on my desktop and then if you spin up the index html i can guarantee you that this is going to work there it is that's my application and i can make it smaller and there it is now i'm toggling again our goal is following i want to take this project index.html with style css logo as well as the javascript file so the html structure the styling the logo that you can see over here as well as the logic i want to take all of it and serve it on my server and i know that the app works so all that is good so let's see what struggles we're going to have along the way so here i have the home page right and instead of getting it from the index.html which by the way i'm going to delete because again this was just temporary now of course i would want to access this one from the navbar app that's the folder name right and then i'm looking for the index html and i simply just need to change my path where instead of getting it index html from the root which doesn't exist anymore i'm going to go to navbar hyphen app and then of course i still get the homepage and as you can see i'm still serving also the contents from that index.html the only thing i did is just change the path that's it and technically we should see exactly the same right but here's the kicker we navigate here and if i refresh what is happening i don't have the logo i don't have the button i mean i do have the button but it doesn't do anything and i can see only the structure and we have quite a few 404s here and actually to give you a good idea why is this happening i want to navigate back to our project and let's just console log the urls and i think this is going to give you a clear message why this is happening so let me go back and i'm just going to refresh one more time and check it out so we're requesting the homepage so that makes sense right so i come here i request the home page and i serve this html file from the navbar app and then i have three more requests i have one for styles one for browser and one for logo now why is that happening well because in my index html if you check it out of course i do reference the style css because i want to add the styling right i do reference the logo because the logo is right here in my folder and also of course i do have the one for the app right the one where i have my logic so this is what happens we send back the initial html content and the browser starts reading the content and every time we have basically a path to our server browser is like hey server give me this resource so give me style css give me logo svg as well as whatever we have here the browser app right so keep in mind that these ones are for icons and actually they are external so this one goes to phantasm that's a little bit different scenario yes the browser still performs this request but of course this is external resource now these ones are on our server but the problem is following are we handling these requests in our create server and of course the answer is no we handle forward slash we handle about and then for everything else we have this 404 so to answer your question yes now manually we'll have to request all the files so lower svg style css as well as the browser app assign them to some kind of variable and set up these paths again this is just an example if you don't want to follow along if you just want to see how it's going to work just sit back and relax but in my case i'm going to request all these resources here and then set up more else if statements where if the browser wants to get the css then of course we'll search css if the browser wants to have logo then of course the browser is going to get local and again if you take a look here in the elements you'll again see exactly why because we have our html structure and then there it is we have style css so notice how browser is going to http localhost 5000 forward slash what well style css right well do we have that path and again the answer is no so let's do this way i'm going to copy and paste and i'm just going to come up with different names here i'm going to say home styles and then the third one i guess is going to be home image and then the fourth one will be home logic so that is going to be my app one then we'll have to change some files here as well so i'm looking for styles css i believe right that's the file name then i have logo svg that's where my logo is sitting so logo svg and then finally let's just delete this one as well and call this browser hyphen app and js so home styles home image and logic and like i said yes manually one by one we'll have to add all these resources so instead of about page i'll just call this styles and the value that i want to check for here is exactly the same like in my browser so they need to match so then of course the browser will get the contents of the css file in this example so i'm going to go with styles and then css now i do want to change right now the content type because am i sending back the html of course the answer is no we're sending back the css so we go text css now let me say this one more time please don't zero in on these mime types if you will ever need them you'll be able to find them within a matter of seconds just type along with me and we're going to be in good shape now as far as the right in our body so in our response that we're sending back are we going to send back html of course the answer is no now of course i want to send the styles right and the variable for that is home styles so that's where my content is for the styles css and once i save check it out now we are moving along in the right direction because i do have the styles so it looks already somewhat decent now the logo is still missing and there's no logic because i don't have the app.js or the logo svg but we are moving in the right direction so copy and paste and you can probably already guess that we'll just repeat over here we'll say if the url is equal to logo svg and i'll say image logo as far as the comment and we're just going to go with logo and 3g and as far as the mime type for this sucker it is image image forward slash svg and plus xml like so and let's go with home and i believe i named this home and image like so and then the last one of course is going to be our javascript so let's say here logic and the resource that i would want to provide is browser app js like so and then the content type is equal to text and then javascript and of course now i would want to send the home and logic so let's save this one and now if i go to my browser and if i refresh check it out now of course we have everything we have the logo as well as the proper functionality with browser app and notice how all our requests are 200 instead of 404 where the previously browser wasn't able to find those resources and now of course we are providing them and if we want to test out the functionality there it is now i can just go here and notice how i can toggle the menu as well and now of course we'll switch gears and start working with express because hopefully it's clear that yes we can set up our server with just http module but imagine a scenario where you have a website with tons of resources and then of course you need to set up every single resource in this matter now i don't know about you but i would go nuts somewhat quickly all right and once we have struggled a bit now let's make our lives easier by getting to know express js express is a minimal and flexible node.js web app framework designed to make developing websites web apps and apis much faster and easier if i have to be honest it's almost unfair how easy and fast it is to spin up the api with the help of express and while it's not officially part of node meaning unlike http module express is not one of the built-in modules at this point in time express is pretty much a standard when creating web applications with node.js express has awesome documentation which we will reference from time to time and you can find the docs at expressjs.com again the site is expressjs.com and as far as the install you simply need to run the command of npm install and the package name is express now they do suggest this hyphen hyphen save flag and effectively the reason why they do that is because in the earlier node versions if you did not add this flag then package wasn't saved to the package json meaning when you push this up to the github the next person who was getting your project well he or she did not have the reference for the package so of course that caused the errors now currently that issue is fixed so this is just a good precaution but technically you shouldn't have any issues if you don't run the command again nothing bad is going to happen if you add this dash save but technically these days you can skip it so just grab the command like so and just navigate back to the project just keep in mind that of course i already installed the express for the express tutorial this is just for your own project if you want to install the express if you set up your own package.json and all that if you want to install the express just run this command now one thing that i would like to mention though is that i'm using version 4.17 so maybe by the time you're watching this they already have a version 5. now at the moment version 5 is in alpha meaning they're still testing everything but maybe by the time you're watching this this is already stable now if that is the case when you run npm install on express of course you'll get the latest version so your version is not going to be this 4.17 now i wouldn't worry if it's for example four point i don't know 24 but if it's five there might be some breaking changes and at that point you have two options if that is the case if the version is already five then you can either reference the api docs for yourself meaning you can take a look at the methods and all that what the version five provides or if you want to use all the methods and properties that we use in tutorial simply install the same version how you can do that well you just need to go to npm install express so this stays the same and again you can remove it you can leave the dash dash save doesn't really matter and after express you go with add and four and then again i'm gonna go with the same one just keep in mind as long as you have four you're not gonna have any issues and then one so this is going to install express with this specific version hopefully everything is clear and now let's get to know express all right and once we have covered the express library basics now of course let's spin the sucker up and see how we can make a server way easier and with way less headache and i'm going to start by removing all the code in my app.js just keep in mind that if you ever need a reference go to the final one and then of course http basics is going to be where we set up the basic http server and then for example the http app example is going to be in the file number two and the way we work with express we start by setting up some kind of variable and of course we'll have to use the require so we go with require and then we're looking for express library again we can do that because we have installed the library but if you haven't then of course you'll get the error keep that in mind and then we go with const and then app is equal to express to whatever we imported and then we invoke it now if you're a bit iffy about this syntax just keep in mind that it is very similar to our previous example where we went with http then created the server and as a result we had our server instance correct so this is similar we're getting a function back from express and we just invoke it and we right away have our server instance with bunch of cool methods now what you'll also see on a web is something like this where since this is a function we can invoke it right away and then just call this one app again this is really your preference but mostly you'll see the first option where we first import the module and only then we invoke it so once we have this setup then of course we have a object with bunch of useful methods now the methods that we'll use the most are following amp.get and i'll just copy and paste here and i'll just change it around a little bit post and put as well as delete and also there's going to be all use and a listen now listen we already covered before in the http module and this one is pretty much the same where we just go with app.listen and then we just say what port we're going to be listening on so in this case of course this is going to be 5000 and then we pass in the callback function so when we instantiate that server we will run this function and a common convention is just setting up a console log where we say that yeah the server is listening on port such and such now for time being we're hard coding this value later i'll show you how we can make this one dynamic so for now i'll just say console log and then server is listening on port and then we go 5 000. so let's save this one and i'll run my npm start and i should see in a console server is running or listening on port 5000 awesome so what about the other methods and the first four methods here just represent http verbs now if you remember when we talked about the http request and response messages well one of the things that we're looking for in the request message was the http verb and yes i set up some more meaningful examples where we'll see all of them in action for now just remember two things first this just represents what the user is trying to do whether read the data insert data update data or delete data and by default all browsers perform a get request so that's why we have here amp.get that post put and delete now all just works with all of them and we'll see that in a second when we set up the 404 page so essentially a response if we cannot find the resource on a server and app.use is responsible for middleware and since it's such a crucial part of express of course i prepared more examples on that where we cover everything from the scratch so for now just remember this is middleware but don't lose your sleep over it we'll cover it a little bit later in the course so we have app.listen beautiful we're listening on port 5000 but since i know that all the browsers are performing a get request i simply go with app dot get and then i need to specifically add two things a path so what resource the user is trying to access and it would make sense if we would start with root correct and then the second thing is the callback function so this callback function will be invoked every time user is performing a get request on our route so basically on our domain and then this callback function gets the same two arguments we go with request as well as the response so this is going to deal with incoming request message and then this is going to deal with our response and in express we go with res and then the method name is send so in here we can pass the string we can pass in the html and i'm just going to simply start with home and page so we save this one and now of course i'm going to navigate to my browser i'm going to say localhost and then 5000 and there it is now we should have homepage if you don't again please troubleshoot because otherwise it's not going to make sense what we are about to do next but if you see the home page you are in good shape so we're listening for get request on our route and then every time the user navigates to the root then of course we just send back the homepage now if you want you can of course go to log and user hit the resource or something like that doesn't really matter and then if you go back to the browser and if you refresh there it is we have user hit the resource awesome and just like in our previous example the basics one let's set up the about page as well as the 404 so i'm going to go back to my app js and right above the app that listen i'm going to go with another app that get and in this case i'm looking for about so that's the resource and of course in here again we have rec and res and then as far as the response well i'll cheat a little bit and i'll just say res.send and we're going to go with about page and then of course i would want to handle the 404 as well so if the user comes to my server and tries to access a resource that doesn't exist well what am i going to send back and we can take a look at the default one so if i'm going to go with about i should see the about page but if i go with for example a contact page let's see what the express is doing and in this case i have cannot get the contact and if i inspect i can clearly see that in my network tab i have contact and this is a404 so that's going to be the default response now i can alter this of course and i can set up my own 404 response so i'm going to go with app and this is the case where i'm going to use all methods because again user can do multiple things on a server and i want to cover them all not just getting the resource or inserting the resource or whatever i want to cover them all so that's why i'm going to use my own method again this just handles all http verbs whether get post or whatever and again this method takes two arguments first one is going to be the path and the second one is going to be a callback function and as far as the path i can say all of them so whatever resource you're trying to access the response is going to be exactly the same if i cannot find the resource then i'll just send back this response so again i have a callback function rec and res in here and then we're going to go with res dot send and just like in our http example i'm gonna go with heading one and we'll say resource not found and let's close the heading one but of course i also would want to add the status right so that would make sense i don't want to send back 200. that would be very confusing so before we invoke send method i can also add status here and as you can see i can chain it so i have res not status so this is where i'll pass in my status code and then i go with send so in our not found example of course i would want to pass in the status code of 404 that is going to be more correct and the same goes here technically we can rely on express and it does a decent job of adding those status codes but a more common approach is explicitly setting up the status code so that way you have more control of what is sent back to the browser so in here i go with res and that send but before i set up that method i set up a status one first and i go with 200 so this just means that the request was successful so similarly i'll do that in the about where i go with status we pass in the 200 and then we set up a chained send so now if i go back to my browser and if i refresh now of course i have resource not found that is my heading 1 and i can clearly see my 404 and if for example i'm looking for about there it is i have my about page as well as the homepage so if we go to localhost and 5000 that's going to be our route that is going to be our homepage all right and we're done with our basic example hopefully you can see that it is already way less code than just using the built-in http module and in the next example you'll see how express truly shines when it comes to setting up a server beautiful we're done with our basic example now let's tackle the big beast our navbar app and the setup for the following examples is really up to you if you're not a fan of retyping something you have already learned you don't have to do that you can just remove app.get all the way to app.all so basically leave the import as well as instantiation and listen as well however i am a fan of repeating something because that way whenever i need to create something from scratch i already have done it quite a few times so i don't have that blank page syndrome where you're like looking at the empty file and you don't know what to do so in my case i'm going to remove everything and we'll start from the scratch so const express is equal to require and of course we're looking for express and then i'm going to set up my app that is equal to express we invoke it and again we go with app.listen and we're going to go with 5000. now i'm not saying that i'm going to do that for every example but i'm just showcasing what is in my approach when i'm starting something new so when i'm learning something new yes i do like to retype some of the stuff quite a few times because that just makes sure that i remember it better and in here i'm going to go with server here's listening on port and we go with 5000 and then dot and in order to set everything up we're going to go with app.get so again i'm looking for the root and of course i would want to start with my index html correct that's the start and we go with app.get so we're listening for all the incoming requests that go to our route and of course we're specifically listening for get requests then we have our callback function rack and res and we'll set up the functionality in a second before we do anything let's also set up all and this is of course going to be for all the requests that will hit 404 so we're going to go with rack and res and here let's say res and then status so let's add here a 200 or i'm sorry four four my bad and then we're gonna go with send and instead of the send let's just go with the resource not found now when it comes to get in this case i would want to send the file more specifically i would want to send back the index.html and in order to do that i need to use send file method that comes with express now in there though i do need to provide a absolute path so we'll have to use one of the modules we covered before and that is going to be a path module so i go with const path is equal to require and i'm looking for path module again we don't have to install it comes preinstalled with node so we are in good shape and then where we have our callback function we go with res and send file method and here let's pass in path and then resolve so path dot resolve remember that was one of the methods we cover and effectively i would want to pass in the dirt name so this is going to be path to our directory because we do need to provide that absolute path and then of course we're looking for our index.html which is sitting in the navbar app so forward slash and then navbar hyphen app and then we have another forward slash index html now if i have to be perfectly honest in this case we can also use path dot join it doesn't really matter since their name provides that absolute path but just to be a bit explicit that we are providing absolute path i went with path dot resolve and then the their name and then whatever is the path to my index html and the moment we save it we'll have the same errors just like in the http module so i go to my localhost 5000 and i still have the same issues i still don't have style css there's no sign of browser app as well as the logo now in express though we don't have to do this whole song and dance like in http module in express i can simply go above all my app.gets and amp.alls and i can go with app dot use and this is going to be the case where i'll type out the code and then i'll explain everything that is happening and we'll pass in the express so this is what we're importing so this is not going to be our server instance instead we're going to go with express and then static that's the method and in here again we just need to provide a path now common name is setting this up as the folder by the name of public please keep in mind technically you don't have to do that you can just point to our navbar app but in my case i will do that i will set up here dot forward slash and i'll call this public so now of course what i need is to set up a folder by the name of public and then all my static resources all my static files i would want to transfer there now don't worry about it i'll cover in length what in a server land means static resources for now what i would want you to do is go back to our folder and that is going to be express tutorial and of course you can do that in visual studio code i just think that this is going to be a bit easier to see so i'm going to create a new folder again common convention is calling this public but you can call it whatever lobster it doesn't really matter and then in my case i'm just going to copy these files so take browser app take logo and take styles if you want you can move them just remember that the previous code is not going to work as far as the http module setup so i'm going to copy these ones and paste it here in my public so now of course i have browser app logo svg and style css so of course now i can zoom out and once i save check it out when we navigate to our route there it is this is our application and what's really cool all those resources are right away available so if i go to my localhost 5000 remember browser was looking for what well it was looking for example for style css if you go here there is a resource by the name of style css and of course in here i have all my css code and notice how we didn't have to set up the statuses we didn't have to set up the content types or any of that express takes care of it all now of course you probably at this point have more questions than answers so let me start clearing them up and first i'm just going to add a comment of setup static and middleware middleware and like i mentioned app.use is for setting up the middleware and we have more serious examples coming up so for time being please don't worry about this line okay so please don't worry about app.use what is express static that is essentially a built in middleware i will cover everything step by step in this video i would want you to understand what the term static asset means and it simply means that it is a file that server doesn't have to change it so instead of our http example where we created a path for every such resource and if i were to have i don't know 20 000 images i would have to repeat the same steps instead since this is a static asset meaning an asset where the server doesn't need to change it we simply place it in designated folder again the common name for those folders are public or static and then we just dump all those assets in there so if i were to have i don't know 20 000 extra images in here i can just dump them and express will take care of it all it will set up the paths it will set up the mime types it will set up the status codes and all of that good stuff so hopefully that is clear static assets are just files that server doesn't have to change and an example of a static asset is an image file here's the style file and also a javascript file and here comes the next question what is this guy with weird eastern european accent talking about because all my life i've been told that the javascript makes my apps dynamic it adds all the functionality so how come this is just another static asset and to answer your question yeah you're right javascript does make our apps dynamic however think about it this is a browser app so it makes dynamic on a browser as far as servers is concerned it is just a asset doesn't need to change now if you're wondering well how to set up something dynamic just please put the pin on that and we're going to cover that when we cover server-side rendering because there is such thing as template engines and the simplest way for me to explain that is imagine the scenario where you can actually log in or in other way just showcase whoever is visiting the site and then dynamically i would display for example name so if the peter logs in then i'm sending back the html with the text of hi peter now if the john logs in then of course i'm sending back the username with the value of john so hopefully you get the gist where in this case notice this is just same old index html that i'm sending back regardless of who is visiting the site but yes there's also an option of setting this dynamically where depending on who's visiting the site or what the user is trying to do i'm actually modifying my file before i'm sending it back so hopefully it is clear how much easier it is to work with express where if we have static assets we just set up designated folder and just dump them all in and static asset just means a file that server doesn't need to change and of course we can start working on our next example nice hopefully we are clear on static acids and before we cover more complex expressed topics i would want to throw a mine grenade at attribute and it goes something like this so if we put two and two together i talked about static assets in the previous video but if we're looking at the index.html isn't this a static asset as well and of course the answer is yes so instead of sending this file we can add it to static assets and we're going to be in good shape and if i have to be perfectly honest with you when it comes to send file if we're using it to send back for example index html actually we use other two methods instead so first i'll show you the first one where we just dump everything as far as the static assets so i'll just add index.html to all my static assets in the public and that will effectively do exactly the same like we're doing here with send file and the other one is going to be using templating engine so of course that one will cover when we go to server set rendering so i'm just trying to showcase that yes there is this option of send file and we might use it from time to time throughout the course but not for sending back index html files so first let me just say that the other option one of the two other options that we'll use the most throughout the course is just adding two static assets like so and then the second one is going to be server side rendering where basically we'll use template engine for that so in order to set everything up now of course i just need to take my index html and again if you want you can just move it or in my case i'm just going to copy and paste so again i'm going to go back to my folder i'll zoom in massively so you can see better so express tutorial there is my navbar app and i'll just take the index.html and i'll copy and paste and now it is in the public so what happens index.html is always going to be a root so when the user hits the server by default server will serve this index.html and since our index.html basically has all the paths to browser app to logo svg and all that we're going to be in good shape more effectively we don't even need to set up this send file option so now of course i can just save it and once i refresh notice how nothing changed i'm still serving my app so we're still in good shape and if you take a look at the network tab notice everything still works correctly i'm still getting all the css all the browser javascript functionality as well as the logo and to answer your question yes that is effectively how you can set up the simple sites you can simply just dump all your files in the public just make sure that you serve them up and that's it and you're in good shape now we still have the 404 but as far as just serving straight up sites with html css and javascript yes you can simply dump them into public you can simply set up the middleware and serve all the static assets and you're going to be in good shape beautiful we are successfully done with the initial express setup and ready to cover more complex express topics before we do that though there's something important i want to mention you see when it comes to express in most cases you'll use one of the two following options you'll use it to set up api or templates with server side rendering now since term api is probably one of the most overused terms in the community and in various scenarios it can mean different things let's start by understanding that in express or in http case when we talk about api we mean setting up an http interface to interact with our data now data is sent using json which stands for javascript object notation and in order to send back our response we're going to use res.json method which will do all the heavy lifting like for example setting up the proper content type and stringify our data the other flavor we have is server side rendering where we will set up templates and send back entire html and css and javascript ourselves and we're going to do that using res.render method now since i'm a big believer in actual examples over slides if you are a bit iffy on either of these flavors just hold on a bit and once we cover some examples i promise you it will all make sense now why am i telling you all of this you see when it comes to more complex express topics it only makes sense if we cover them properly using one of these flavors instead of just bunch of random examples and the option i picked is the api one so in the following examples we're going to construct api response using more advanced express setups the reason why i picked apr route is because i believe it lets us focus more on the actual express since templates by themselves add a bit more unnecessary overhead especially while we're just starting out with express with that said let me be very clear if you grasp the concepts with api so using the api flavor you'll have no problem implementing them with templates as well since for the most part express concept setup is exactly the same we'll cover server side rendering later in the course so you'll have to wait a bit for the actual example and since we're going to start with api let me just stress the main point one more time and how it looks like in a real world so like i said the main idea with apis is that our server provides data and what that means that any front-end app that wants to access it and use it can simply perform a http request and using our data set up the api and functionality how does that look like in a real world well if you navigate again back to course api and of course not the slides slides are just images but if you take a look at any of these examples you'll notice something interesting where we're sending back the json and you can clearly see that if you go again to your browser's network tab and here again let's refresh and you'll see that this is our response react tabs project so again the full url is course api.com and then react tabs project and if we take a closer look we can see that this is the response that we're sending so we're sending back a json data and i can clearly see that in my headers so in response headers as you can see content type is application json now where is this data used if you took either my react course or the vanilla javascript course you know that in the course we build quite a few projects where we practice data fetching either using vanilla jazz or react and in some examples we use external apis and in sum we use the apis that are here in the course api so for example with this react tabs project if you navigate to react project nutlify.app and keep on scrolling keep on scrolling you'll hit the tabs project and here this is the app that we build using the data so again on a server i set up my data i set up the api and i share the data so i create the http interface and then the frontend app just simply grabs this data and again if you want you can check it out here if you refresh notice this request request goes to course api react tabs project so we grab the data on a front end and then we set up the functionality as well as user interface hopefully this is clear from now on we are going to be responsible for sending back the data so now since we're setting up the server it's not going to be our responsibility to do something with it like we were doing on a front-end in this case we are responsible for setting up the responses so we're going to be setting up apis that our http interfaces to interact with our data not bad not bad i think we clearly covered our two options so one is sending back the json data and the second one is server set so why don't we start by covering the most basic json response and here's what i'm trying to mimic if you go to course api and then if you look for the tours project you'll hook the url of course and here you can see that we're getting back a json data it is an array and each object represents a tor and if you took my react course you know that we were practicing data fetching in react and effectively we hit this url and we got the data we got our json data back and then we built an app using that data but again the whole point here is following where it doesn't have to be react it can be vanilla javascript application it can be swelled framework it can be any setup where you're able to fetch that data so in here on the server we just share the json so in this case of course that is stores and then anywhere anyone who wants to access this data they can just access it and build something using that data and that's why it is so so powerful and essentially this is what we're going to do we're just going to send back first a most basic array and then we'll see how we can make this more dynamic please keep in mind two things first of course eventually we'll use database for that and of course i will mention that probably 20 000 times as we're building these examples and the second thing that i would like you to understand that when it comes to express basics so essentially how we set up the server it doesn't really matter whether we're using server side or whether we're using json again if we understand the principles we'll have no problem using any of those options so first what i would want is to navigate back to my project and again this is going to be the time where i do write everything from scratch but then starting with next example i'll just use some options that we already covered so for now yes i'll remove everything and again we'll set up express one last time so we're gonna go with express require and express okay awesome then const app is equal to require or i'm sorry not require we need to invoke the express like so and then let's go with app.listen port 5000 and then let's call our callback function and then let's go again with console.log and server is listening on port on port and of course the port number is 5000. then again i want to set up app.get because that is the http method that all browsers perform by default so i'm going to go with app.get and i'm not going to go with specific path just keep in mind that you can and of course we'll do that later for example i can go here with api and then i don't know i can call this product or whatever for time being let's just make it simple and we'll just handle all the root requests so that way we can save a little bit of typing in the browser and again we have our function our callback function rack and res and as far as the response we're going to go with res and then the method name is json now we will go to the docs just so you understand where i'm getting this information from but before we do that let me just tell you that i might omit here and there the status one just so we can save a little bit of typing but don't worry once we go to some more serious examples of course we'll still use the statuses because in my opinion that is just a better approach where we actually have control over the status and as far as documentation if we go back to express documentation we're looking for api reference again we are using four point something so we are using version four so make sure you look for the same one and don't confuse with express json so this is going to be a middleware that we pass in effectively we're looking for response in a docs and then we're looking for this json option so res object as the json method and what happens we send back the json response and this method sends a response with correct content type that is a parameter converted to a json string using json stringify this parameter can be any json type including object array string and blah blah blah so hopefully you get the gist so the only thing we need to do is go back and for example i'll provide an array where there's going to be two objects and first one will be named john and the second one will be susan so another object and we'll say name is equal to susan and we have our most basic api so if i go back to my localhost 5000 and refresh there it is so now anywhere in the world i can access this data and build something using this data now there's tiny caveat when i say anywhere in the world there's still going to be at the moment a course error and i'll cover that once we actually cover middleware so again please please please please be patient we will get there but hopefully you get the gist where this serves our data and now we can just access that data and build the front-end app using this data now this default setup is nice but of course we can do something more meaningful where if you take a look at the folder you'll notice this data js now what is data.js it is simply a file with some arrays and the first array is going to be products and here as you can see i have objects and then each of these objects represents a single product and all the way in the bottom we're exporting both arrays we're exporting products as well as the people array that we're going to cover a bit later so now what i would want to do is import product array in my address and then instead of hard coding this value like so where i just pass in the array with two objects i'll just dump the whole products data so let's go with const we already know how to do that now since i'm exporting multiple things since i'm exporting an object i will be explicit of what i would want so i'm going to go with product and basically i'm destructing right away i'm going say product is equal to require and remember the file is data js like so and then instead of passing array directly i can simply go with product and what do you know when you navigate to the root there it is now we have more meaningful json response where actually this is a product data so on my front end i can grab it and i can build some kind of nice front end using this data now lastly before we go let me just showcase that of course there's going to be a content type set up correctly as well so if you go to network tab and again if you refresh localhost like so and take a look now of course what is the content type that is application json so now of course we're correctly getting our json data so hopefully you have a clear understanding how to sound json data so now of course let's make things a bit more interesting and cover some more advanced express topics nice once we're familiar with the most basic json setup now let's build a more meaningful api and in a process we'll cover route parameters as well as query string parameters and i would want to start in following way where essentially i'll leave all this code but when it comes to my route when it comes to my home bridge i'll essentially send back the heading 1 with the link as well and that link will direct a user to a forward slash api and then product and then later we'll cover the params as well as the query string so let's start with sending back html instead so i'm not going with json one and i'm not gonna send back the file i'll go directly and i'll say send and here we have the string of course so i'm gonna go with heading one and then home page then i'll make sure that i close because i believe in one of the previous videos i believe it was the express basics i think i messed it up here notice i didn't add the closing one so now everything is correct and now i'm gonna go with my link then as far as the href i'm gonna direct a user to api and then forward slash and then of course i'll also set up a text here so products and i'll close my link so that should do it that is my home page and of course if i go to localhost 5000 there it is i have my homepage and once i click the link i navigate to api products now of course the moment i have the default response from the express meaning the default 404 response where the resource cannot be found and as i said note if you want to take a look what response do they send again go to the network this is going to be very very useful tab refresh and take a look at their response so notice the response that's the html that they send back so cannot get and then api products now we already know why there is this get the http verb because that's the method that the browser performs okay awesome so now of course our job is to set up a get request for this resource so we go with app.get and i specifically want to handle api and product so this one just looks a little bit more realistic so in here i go with api and products and keep in mind of course those values need to match otherwise you'll get that 404 again i have my callback function and now of course i would want to send back the product however in this case we'll make it a little bit different where previously notice the product we send back pretty much the whole thing right but a more realistic approach is following where when you're requesting a bunch of data so when you're requesting collection of the data you're not always returning everything for that one specific product and to give you a real world example again i'm gonna go back to my react projects and i'm simply using them because this gives you a visual representation during the course we built a e-commerce and then in the products page notice how we're fetching the products but you need to keep in mind one thing where we're only fetching about the product the title the price the image and i believe also the id and only when i go to that single product page this is where i get the rest of the data whether that is for example a stars the reviews the description the availability and all that stuff so what i'm trying to say is when you're requesting a collection of data there's going to be cases where i simply want to send back some minimal response so for example again that could be name image and the pricing scenario and only if i look for this specific product then i send back everything and in order to mimic that in our example in this response what i'm going to do is i'm just going to iterate over my product i'll use the map method and i'll just remove my description so when i'm sending back the product it's going to be without a description so again if we were to send back everything i would simply go with response json and then i pass in the product so again if we go here and if we refresh now everything is cool i'm getting my product on the api product route however i'm going to make it a bit more realistic and we're going to go with const new product is equal to product dot map so i'm mapping over and i'm creating a new array and i'll reference each item as a product and then as far as the return well first i want to structure the properties out of the product and the reason why i can access them is because those are the names that i used when i'm setting it up so id name image and all that and that is equal to the product again i'm just using simple javascript structuring and then as far as the return whatever i'm going to return from my function well that is going to be the new value so now i'm going to go with id name as well as the image and once i have this setup in place instead of returning product now of course i'm going to go with new products and if i go back to my browser there it is so now i'm getting a collection but i'm not sending everything that i know about this specific item so i'm being selective of what i'm sending back so yes there is a resource by the name of api product and we're sending back the array but we know that if the user wants to access that description he or she will have to look for a specific product and in the process we'll cover what are the url parameters all right so we're successfully sharing a list of items so now of course let's take a look at how we can provide info about that one specific product so for example if i navigate to product and then forward slash and one and then i'm going to get only the info about this first product because it has the id of one and not only i'll get these three properties but also get the description and our initial approach would go something like this where yes i see the product okay beautiful and we already know how to set up the route now since i'll delete it eventually anyway i'm just going to copy and paste so we can speed this up so i'm going to go with api products and then forward slash one that just means that i'm going to be looking for item number one in here and then instead of map we'll use the find method so i'm importing all my products and in order to get the single product i'm going to write the following code where we're going to go with const single product and don't worry we will reuse this code so it's not like we're just randomly typing something so let's go with products and then find now again i'll reference each product with a parameter of product in my callback function and then if the product id product id matches one because that is my route here then of course i'll return that single product so i'm going to say single product and technically this works so notice now of course i have only info about this one specific product and i have the description however it feels like using bazooka on a cockroach yeah it gets the job done but probably is an overkill because keep in mind at the moment we have only four products so yes if i really wanted to i could set up four routes but what if i have hundred two hundred three hundred well that's not gonna work and in express we have something called route parameters which essentially is going to be way better solution so instead of hard coding this 1 2 3 or whatever id we want we set up a route parameter and it's going to look something like this where i go with my route and then i have forward slash and then i go with colon and then whatever name out one so think of this as a placeholder so you can call this bobby lee you can call this chicken burrito in my case i'm gonna go with product and the id just to be explicit of what i'm expecting over here but again naming here is really up to you and what is more important is the fact how we can access it now if you want you can actually console log the request object again this is just going to be a giant object and for now i'm just going to leave this one the way it is so i'm still going to be returning a product number one and also let's look for request and then we're looking for the params property so let me count to lock this one and then again once i navigate back and if i refresh in the api products number one what you'll notice again this giant request object where we have bunch of useful properties and methods and of course i'm not going to cover all of them right now but similar to http of course in the express we also have access to bunch of useful things in that request object and one of them is the params so check it out now i have this product id and the value is one now please keep in mind one thing that whatever you're going to be setting up here in the url as that route parameter is always going to come back as a string and this is important in this case because if you take a look at our data the id is a number and of course we'll deal with that in a second and whatever we set up as far as our name is going to be right in here it's going to be in this request and then parameters object so now of course what i could do is i could just destructure it from the params and then use it in order to find that specific product so that way i don't have to hard code products number one product number two and on and on and on instead i just set up my route parameter and just come up with whatever name i would want just make sure that you add this colon here and then we'll access that value and get a specific product so i'll leave these two suckers for your reference just in case you would ever want to console log them and we'll simply go with const and the name is product id and that is equal to request that's my request object and params then i'm going to use this product id to get my product but remember it is a string we can clearly see that and in fact here in the array well the ids are numbers so if we'll just try to search it the way it is of course we won't be able to get our product so instead what we want is pass in the number and then product id now of course if your ids are set up as strings which is somewhat typical setup for the databases and all that as well as the headless cms is then of course you don't need to worry about it then you can just pass in the string and now of course i'm going to be able to get my one product so now if i go back and if i refresh everything still works and if i go to my url and start changing these values hopefully you can see that now of course i'm getting a different product now i'm getting product number two and i go to product number three and on and on and on so now with these few simple lines of code i can access any product in my array now of course there's also a case where we cannot find the product because keep in mind here i can type whatever i would want so i can go with products and then let's imagine that the user types abc now do we have a product with an id of abc of course the answer is no so what's happening over here now i don't get anything back right well i don't get anything back because if i go to log and then single product let's see what we're going to get back again let me refresh abc and this one is undefined so that's what we're sending back as a single product so what would be a solution well a solution is setting up a if statement here where i say get me the single product if you cannot find that single product if basically that product doesn't exist if the id that the user passed in does not make sense you cannot find the product with that id then return 404 so how's that going to look like well we can go here if and then single product so we set up a if condition and of course i'm going to go with if single product doesn't exist so i'm going to add exclamation point and of course this is going to be our case with undefined this will be true if it is undefined and then we just go with a return res and in this case i will add a status because that is extremely important that i go with 404 and then we go with send and product does not does not exist like so now if everything is correct then of course we go with res and json so in here i say return and res dot json so once i go right now to product and then abc there it is now of course i have proper 404 product does not exist and if i again take a look at the tab and i have my abc now if i'm going to navigate to a route where i can find the product then of course i'm going to get my proper product response so whenever you think of route parameters think of them as placeholders where user provides a data and then using requests and params we can access that data and then set up some kind of logic and before we continue and cover query string parameters let me just mention that route parameters can get way more complex than this so for example imagine this scenario i can go with app.get again i need to come up with some kind of routes i'm going to go with api then products so i'm looking for specific products so i'm going to use a route parameter let's call this product id then i'm going to look for all the reviews and then maybe there's a review id so review and then id and now of course again i have rec and res like so and then i'm simply going to send back some kind of dummy data but i would want to console log the rec params just so you understand how everything works and now let me send res.send so res not send and i'm just going to say simple hello world let's save this one and again in the browser let's go here we have products again some kind of id whether that's abc whether that is a number in this case it doesn't really matter since you can see that there's not much functionality in there but we need to type in here reviews and then for example the review id would be i don't know abc so once i navigate here of course i'm going to get my hello world and then in the console notice how i'm accessing all of them so i have the product id as well as the review id so again they can get way more complex than just this simple approach and one more thing i would like to mention this reviews though is hard coded so if i go back i can change the abc and 4 however i would like but if i'll change from reviews to review i'm going to get a 404 why well because review is not a route parameter so that's not a placeholder so if this is incorrect then of course i get d404 hopefully that is clear and now let's talk about the query string parameters all right and once we're familiar with rot parameters let's talk about the query string parameters or they're also called url parameters and essentially that is a way for us to send small amounts of information to the server using the url now this information is usually used as parameters to for example query database or filter results and that's really up to the people who are setting up the server they decide what parameters are going to be accepted and what functionality will depend on those values and to give you a real world example let me go to my search engine and i'm just looking for hacker news algolia api so when you're working on a front-end app i'm not sure whether you worked with this api but that is a very cool api and essentially it's going to work as a good example of how we should be setting up the server and this is as a side note but notice the url here so they go with a domain which in our case is of course localhost 5000 but here it is actually a algolia domain so algolia.com forward slash api like i said that is a pretty common practice then a version number and then whatever list you're getting so in here it is items now check out this one doesn't that ring a bell of course that is a route parameter where they say yeah here's the list of items but if you want to be more specific please provide the id and then if you keep on scrolling you'll notice the same thing with the users again we have the main domain api version one users that's the list and then if you want to get a specific one then of course again there is a route parameter now this is just to showcase that i'm not randomly coming up with those things no that's how actually the servers work in real world and let's keep on scrolling and now we come to this interesting part where we can sort so we're getting the data from the algolia api but then in my app i can sort i can say hey you know what get me specific hacker news story or get me stories based on some kind of search term and hopefully you get the gist where instead of just grabbing the whole thing i can say you know what get me all the stories that match through so again we go with the url and this is really up to you how you set this up in their case they use search and then here we have this question mark and whatever is after this question mark is not technically part of this url meaning it's just a way for us to send that data to the server and then server decides what to do with this data so the url is still this one the one that ends with search and then we have a question mark and basically this is just a specific info about the data that i'm requesting so here the user adds a query parameter and then the value is full and then also has tags of story and that means that we're going to get all the stories matching full now what else you could set up here in a query string pretty much anything a pretty typical is going to be page for example if you have a list of things and i don't want to get 100 items at a time i can say you know what split it up in pages and get me initially page number one and then only if the user clicks on a button that fetches the page number two then i get the second page then for example in here they have hits per page so that is going to be how many items per page so again after that question mark if the setup is supported by the server then of course you can add those key value pairs and the way we add them as you can see is by using key value pairs so we have question mark and then we have a key which in this case is query and then the value now before we continue let me make something very very clear it's not like you can randomly search the web and just start adding these query string parameters and then expect that as a miracle you'll just get the data that you're looking for a as far as the keys they're designed on a server so if i'll set up a key of chocolate milkshake algolia api is going to be like i don't know what you're talking about and the same goes for the value so where i'm going with this now we are in charge of that server so it's up to us to handle those query string parameters and i'm going to go back to our project and i'll purposely set up a new route please keep in mind one thing where a pretty typical setup is adding this to the list so again we'll look for specific property on our request object and then if that property is provided then of course we return a more detailed response meaning there's maybe some filtering or something like that but if not then we'll send back all the products now i'll purposely set up a new route just so we don't jam all our code in this one route but then in the next video probably i'll show you how we can combine both routes so let's keep on scrolling so this is going to be our more complex params example and let's go with app.get and again the route is really up to you i'm going to go with api now in order to make it interesting i'm going to add that version 1 just like the api of algolia has it and then i'll say query now i don't need to add question marks nothing like that i just set up query that is my route and then i have my callback function rack and res now in this callback function in order to access those query string parameters i need to go with rec and query so let's go with console.log and we're going to look for request and not params sorry we're going to go with query over here and again let's go with simple hello world just so we can speed this up and then if i go to the local host and more specifically i'm going to look for localhost then 5000 then api then version number one and then query and then if i add this question mark i can add as many query string parameters as i would like so here i'm going to go with the name that will be equal to john then in order to combine them we just add this ampersand so we're going to go with name john and then id4 just keep in mind that you can add as many query string parameters as you'd want and then once i navigate there at the moment i'm just going to get the hello world so that's my default response from this url but in a terminal notice i have name john and id number four again this is a string and this is going to be important in a second but what this allows us to do is access those parameters and then based on them do some kind of functionality now first of all i would want to change this around a little bit where i'm not going to be looking for name or id i'm going to be looking for search query parameter as well as the limit so if the user wants to search for a specific product he or she needs to provide that search query parameter as well as limiting where the user can limit of how many products they are getting back so let me navigate back and just to showcase that so again instead of name i will zoom in we'll say search is equal and then whatever i would want so in this case i'm just going to go with a so effectively this will return all the products that start with a and then the second one is the what that was the limit right so i'm gonna say limit and for now let's just go with two of them so this will return two products i'll zoom out and again i have search and i have limit after you so now of course let's set up that functionality and we'll simply start by creating new instance of those products i'm gonna go with let and you'll see in a second why so say sorted product and in here we'll use the spread operator so we imported the product and now i'm just going to copy the values so this is going to be my new array and the reason why i'm using let because we will modify this value a bit now instead of just cancel logging the query i'll comment this out and we'll set it up as const and then again i'm looking for two specific keys i'm looking for the search and i'm looking for the limit so if the user doesn't provide them well then we'll send back all the product so we're gonna go with query like so so i can see the search and limit beautiful and now instead of just sending back hello world i'm going to check if the search is in my query string parameters then i would want to filter my product so i'm going to say if and then search like so and we're going to go with sorted products since i'm using let i can do that i'm going to go with sorted product and then filter method again straight up javascript again i'll call this a product like so and what i would want to return are the products that start with the value of my search term so here i can say return product and name so if the product name starts with now again this is straight up javascript and i'll pass in the search if that is the case that is going to be my value in stored product and i can right away check for the limit as well where i'm going to say if and then limit and if it exists so if the user has provided it again let's go with sort product and filter more and in this case i'm going to use the slice method where i'm just going to get specific items from the array so i'm going to start with 0 and then remember we're getting a string so we need to go with number and then again we'll pass in the limit let's go here below both of them and let's just say res dot and then status and we're going to go with 200 like so and then a json response now when it comes to json response we're just gonna go with our sword product right so we go back and let me just showcase something where if none of the query string parameters are provided i'm gonna send back my whole data why well because i copied my products right both of them were false both of them were undefined and as a side note there is a error here cannot send headers and i'll talk about it actually in a second that is one of my next topics so let me just deal with this hello world by deleting it and we're going to be in good shape but i'll cover why we got this error and what gotchas you should be aware of so let me go back again let's see again we're getting all the products because the user did not provide that specific query string parameter so if we right now navigate to the url and i'm gonna start with a limit and if in the limit i'm gonna say that i'm only interested in two products check it out now of course my limit is two so i only have two products and if it's three then it's gonna be three and then four and hopefully you get the gist where whatever value i provide here in a limit well i have the functionality for it now keep in mind again name needs to match if this is going to be limi instead of limit again i'm just going to get back all the products regardless of what is my value and the same goes for the value of the query string parameter if this is limit but for example i decide to pass in abc nothing i get empty array why because my value wasn't what my functionality was looking for and similarly of course we can add the search option as well and i'm purposely showing them one by one so you don't get confused so let's say search and again the functionality is set up where you need to provide a starting character so in my case i'm looking only for the products that start with a and there it is i have two of them now if i want a limit i can just add and here and let's just type limit and i'm only going to be looking for one product and if i add this limit one there it is now i only get one product now there's also obviously going to be the case where we return empty array why well because i could go with search and look for the products of b and unfortunately when it comes to my product data i don't have products that start with b so we can handle that instead of sending back empty array i could check what is the length of my array and if for example it is less than one then i explicitly send back the response where i say yes the request was successful but i couldn't return any product so we can go with if and then sorted product if the length of this array is less than one if it is less than one then of course i can just go with res dot status now this is one gotcha where you're not sending back the 404 you're not saying the url doesn't exist or the resource doesn't exist in this case you're trying to filter the product but nothing came back so whatever query string parameters were provided they didn't yield any results so you're simply saying status and then you can go with send and we can go with no products products matched your search like so so we can go here and then if we refresh again with the same ones we have no product match your search so that is one option you can send back the string but a more common one is this one where i'm going to comment this out for your reference again and instead you go with return and you're going to go with res dot status and again we have this error in the server and again i'll talk about it in the next video why we have that one so we're going to go with res dot status and we pass in the 200 and instead we send back the json one and in that json again you can pass the string if you want but a more common approach is setting up the object where you explicitly say that the request was successful or a failure so you go with success and that is equal to true and then again you come up with whatever name you would want a generic one is data and then you send back the array again you are in charge here you can really do whatever you want i'm just showing you a pretty common approaches to the situation so again i'm looking for some kind of product using my query string parameter now unfortunately server can return any data meaning any product and then of course i just get this success true because the request was successful there was nothing wrong with my url however i'm just yielding a empty data so that's it i can just delete it and if i don't provide anything then i'm going to get all the products hopefully that is clear how the query string parameters work and now we can cover a few gotchas all right and two things that i would like to emphasize are following first remember those errors that we're getting in a server when we're setting up if conditions in javascript if we don't explicitly return then of course javascript just keeps reading the code correct so if i'm going to omit that return i'm actually going to get the server error where i send back one response and then javascript just keeps reading the code and then express is confused express is like hey wait a minute i already sent back the response so while you're sending another now keep in mind that it is happening in the same request so you cannot send basically two responses in the same request one after the another yeah of course you can send one based on the condition so for example if there are no products you send back one response and if you can yield some product then great then you send the second one but you cannot send both of them one after another in the same request and if you want to see that error again in action go to the query you'll add a question mark here and we're going to go with search and again it is equal to b for example that is my value that's the starting value that i'm looking for and once i do that notice yeah i'm getting back the success true and data but again i have this big fat error in my server and it says cannot set headers after they are sent to the client so we can have only one response per request and in order to avoid that we just go with return so always always when you're setting up the condition make sure that you go with return so that way we are returning from our callback function and one we set up over here and that way you'll avoid those errors now of course in this case there's no more code to read so yeah it is a better practice if you just put this return here but you won't get the error since again there's nothing after that and one more thing that i would like to mention normally you're not going to set up a separate one just for the query yeah there might be some cases maybe there's some apis who do that but normally again you can just add it to where you're getting a list so basically if there's a query beautiful you're maybe gonna sort that data you're gonna filter it you're gonna i don't know set up some pages or whatever and if no query string parameters are there then you send back the whole product and if you take a look pretty much nothing stops me here from just changing this to api and products and the functionality is going to work where if there are some query string parameters present beautiful notice how we're filtering our product if not then i always send back these products anyway and as you can see those are just copies of the products that are coming from my data js hopefully that is clear and now let's move on to our next topic nice and once we're familiar with route params and query string let's really kick things into gear and talk about middleware in express.js express middleware are functions that execute during the request to the server each middleware function has access to request and response objects and when it comes to functionality literally sky is the limit in order to hammer this home i have prepared quite a few examples where we cover middleware step by step since in my opinion actual code examples are far more helpful than text based explanations before we continue though let me just stress something middleware is literally everywhere in express you can even make an argument that express apps are nothing but a bunch of middleware functions stuffed together to make one nice express cake or dessert if you are in that sort of thing and since that is the case middleware is not one of those topics you can just skip or avoid it is at the heart and soul of express so please don't dismiss it with that said since you'll encounter it more than once if you struggle with it in the beginning don't panic the more examples you'll do the better you will understand it now let me start by cleaning out my app.js and this is going to be the case where i will leave the code at least some of the code from the previous lecture so let me delete all the middle part and i'm just going to leave express we are instantiating our app and we're listening on port 5000 and let's just start by adding a comment here for your reference so there is a incoming request and so far we have been just sending responses right so what middleware does it sits in between hence the name so middle where over here and then we pass the response so the request comes in we'll do something so we'll have access to the both to the request and response we'll do some kind of functionality again the most basic you can just cancel log something and then we'll send out the response and again i know it probably looks confusing at the moment but trust me the more examples you'll do the better you'll understand and let's start by simple scenario where i have two routes i have the home route and i have the about route and in those routes i would just want to log the method that the user is using the url that the user is trying to access and for example a date and if you think that's silly there's actually npm packages that do that because as your express apps grow bigger and bigger it is very useful to see those incoming requests in that manner so let's start here by setting up add.get again this is going to be my home page and for time being i have my callback function i pass it in and i just go with the res dot send and i send back the home and i'll do the same thing here with my about so there's going to be two routes at the moment home and about unless it's just going to say about so i'll save it and it's not going to be surprised if i navigate to localhost 5000 if i refresh this is my home and this is my about again something we have covered already before now here's the kicker if i go with logger and if i set up that functionality in the route forward homepage i'll also have to do that in the about so let me showcase that so i have request object and in there i have method i have url and i'll simply set up the year because i don't want to deal with javascript types so let's go with method now that one was on request dot method property then we also have the url so url here and that is going to be a request url property like so and then like i said i'm going to go with const and i'll name this time but in order to make it easier i'm actually going to get a full year so i'm going to go with new date and i'll invoke it and i'll say get full year and invoke it as well and of course i'm sending back home yeah that is nice but before i do anything i would also want to cancel console.log all three of them so method url as well as the time like so so i save it and now every time user is gonna hit this resource of course i'll see that in a console log so there it is if i go back to my home page like so and if i refresh quite a few times there it is now in a console i can see that the method was get so the user was trying to get the resource and then the path was the homepage that's my url and then the year is 2021. okay awesome but here's the problem if i want to have the same functionality in about what do i need to do right now well again i need to copy and paste now if i have 15 routes does that sound like a reasonable approach of course the answer is no a better solution would be if we set up a function and in that function we have all this logic and then i can just attach it really nearly to all my routes and when i say well in italy it just just means that for some routes i maybe want to attach it and for some maybe i don't so here's the deal i can go above both of my routes and i can just simply say that there's going to be a function by the name of and for time being we're not going to look for any parameters but yes there will be there and then we just take all our i believe four lines of code right and we just cut it out and pass it here okay awesome and now of course where do we attach this function so we don't have to duplicate our code and the place is following where we have the path and then we have the callback function now in between them we can stuck a middleware so in this case as you can see i'm referencing the function please keep that in mind so i'm going to go with logger that's my middleware function but now there's the second question well in the logger i'm accessing request object right so how can i do that because at the moment i'm not passing it in well the good news is that express passes it in to our middleware function so in here i just set up the reference for my function and express will do that behind the scenes it will supply the rec res and also a next and you'll see in a second why we need this next function as well so again we don't have to do anything we just pass here the middleware express supplies them but of course it's our job to access them as parameters and then set up our logic so for them being i'm not going to do anything with next i will save and we should see something where in the console i'm still going to get my log but the problem is going to be in the browser so if i navigate back and if i refresh notice something where i have this spinner okay so what's happening here well i successfully logged but i didn't pass it on to the next middleware so here's the deal when you work with middleware you must must must must must pass it on to a next middleware unless you're terminating the whole cycle by sending back the response and don't worry there's going to be examples where we do that as well so for now just keep in mind that when you have a middleware where you set up some kind of logic unless you're sending back to response yourself for example since i have access to response i simply can go with res dot and send and again i'm going to come up with testing or whatever it doesn't really matter what we send back if we refresh notice it doesn't really matter if i try to access the home page since i have my middleware i'm actually sending back the testing and this is why the middleware is so so powerful because you can literally do whatever you want over here you can set up all kinds of cool logic and you have two options either you pass it on to the next middleware which in our case of course are going to be our methods our get methods or you simply terminate the whole cycle and you just say res dot send and i'm sending back my own data so let's not be brutal over here i will actually remove this line of code and if i want to pass it on to the next function meaning in our case that is going to be my method app.get i simply go with next and we have to invoke it again please keep that in mind there's going to be more functionality later in these middleware functions but you always always either you terminate so either you send back your own response or you pass it on to the next middleware that is very crucial so now if i go again to my homepage there it is i successfully navigate to my homepage i can clearly see that that is my response and i also successfully logged in my console the method the url as well as the full year and now of course instead of adding this logic line by line to every request simply can go and i say yep i would like to invoke the logger here as well so if we go to logo host 5000 and if we're brave enough and we navigate to about there it is now i have get request about url as well as the full year hopefully that gives you a good initial understanding how the middle works and now i can talk about more complicated topics beautiful we are familiar with the middleware we have our first middleware function but there are two issues with this current setup first our appdress is getting somewhat clunky because i mean we have this logger then we have the methods it's definitely nicer if we have this logger function in a separate file it's just going to keep our app.js lean and in turn it's just going to make it easier for us to navigate and essentially work with our application and the second issue what if i have 50 more routes and i don't want to add this function manually to all of them wouldn't be nicer if there would be a method that essentially just adds my middleware function to any route and of course the answer is yes there is such a function in fact we used it a few videos ago now let's start though by moving this sucker into a separate file so i'm gonna go to my not navbar app sorry this is what happens when you have a bunch of projects open meaning a bunch of folders open let me go here where i have my app.js and i'm just going to create a new file and this is still going to create it in the final sorry so let me go here and i'll create a new file and i'll call this logger js now if you really want you can add the middleware there in name as well but in my case i'm just going to add the name of my function then i'll cut it out and what's really cool that we know how to export this right so we have cons logger and then we go with module exports and we'll just set it equal to our logger so now we have default export that's our logger so of course in the app js i simply need to go with const logger is equal and then i require it i go with logger and if i navigate to localhost 5000 i still should see in a console my log and if you do then everything is correct so that's the first part now the second how can i apply this logger to all my routes so for example let me just copy and paste these ones and i'll say api and then product and then api and i don't know not about maybe items again doesn't really matter what you place here i'm gonna go with products as well as items again i can add them manually but the more routes i'm going to have well the bigger issue this is going to become right because for every route i need to manually add this logger so a better solution is this one where i select all of them i just remove them like so now of course if i go to any of these routes i'm not going to have anything in a console but there is a method by the name of app dot use and in that app.use this is what we do we pass in the middleware so we simply go with logger and once i save check it out now if i go to about for example or if i go to home or api and then products and hopefully you get an idea all the time you'll get this log in console why well because app.use will invoke this for any route now please do keep in mind two things first order matters here if i'm gonna place this below app.get and if i'm going to try to do that in a home page i'm not going to see anything in the console why well because i invoke my use only after get and express everything goes in order so if app get is before the used one the one that applies to all the routes then yes well first we'll hit the home route and then we'll send back home so there is no logger so that's why you'll see all the middleware functions all the app.uses at the top of the document so you'll have your middleware functions first and only then you'll have all your roth methods whether that's get post and you get an idea so that's the first thing that i would like to mention now the second thing that i would like to mention is the fact that we can add here a path so if i go to app.use that's my method and instead of providing only one argument which in my case is the logger i can set up a first one and that is going to be path and i just need to come up with a value now in my case i'm going to type api and you'll see e in a second why so if you save with an api you'll notice something interesting where this is going to be apply to both of them to the products as well as the items so here's the deal once you apply this path over here basically it's gonna apply to any route after this api so for example if i go with api and then some crazy one home about and then products all the time is going to keep on applying this middleware so that's something new right because previously we worked only with a specific route so forward slash or about or products here in this case so of course these are different now when we add this path to use then of course it's going to be applied pretty much to anything that comes after the path that you provide over here so in my case since i provided api and of course it's going to go for any path that's after that now if you want to find out more info about app.use i suggest navigating to docs again we're looking for api reference in our case that is four and if you take a look at the app.use mounts specified middleware function or functions and we're gonna cover that later as well at the specified path and middleware function is executed when the base of the request path matches so this is going to be our base and then whatever comes after will still invoke that middleware function and if you omit the path then it's just going to be applied to all of your requests so if i were to remove the path now it's going to be applied to home about api product as well as api items nice we're familiar with app.use and now i want to make our example even more interesting by adding another middleware function and in the process we'll take a look at how we can execute them in that use what is the syntax in order to add it as well as what is the execution order and let's start simply by creating a new file and i'm going to call this authorize authorize dot js again i'll zoom in just so you can see that is the file name and in here i'll just set up a function similarly to how we worked in the logger one so i'm going to go with const authorized or authorized it doesn't really matter now it's going to be a middleware function so of course i know that i'll have access to rec res as well as next and then in function body for time being i'll just invoke next and maybe i'll cancel log i'll say log and authorize like so okay let's save that one remember that we need to export it so module exports and that's equal to authorized awesome and then in the app.js i'll just copy and paste and i'll say authorize like so and of course the file name is also different it's not a logger so we can go with authorize and once i have this setup in place the way we execute multiple middleware functions in app.use we simply place them in the array so i'm gonna go with my logger first so logger and then we're gonna go with authorize and now once you navigate to a localhost 5000 again any of them in this case because notice there is no path first in a console i'll see this get and then authorize and that's something to keep in mind where they will be executed in the order so if we flip this one if i go with authorized first and then i go with logger then of course in the console i'll have the opposite order where i'm going to have authorized first and only then get so that's something to keep in mind now i'm going to go back to my previous setup the logger and then authorized and now let's take a look at how we can have the if condition in our middleware function now before we do anything let me just stress something very very important where this is just for demonstration purposes this is just an example and it's not how we're going to authorize users in our express applications i just don't want to overwhelm you from the get go so i'm just going to show you simple example using the query string but again this is not this is not how we authorized users in our express applications and with that said i'm going to navigate back to my authorized middleware and in here i'm just going to set up a query string so i'm going to say if the user provides a query string in my url then i'm good to go then i'll send back the resource that the user is requesting however if the user doesn't provide the user query so query string parameter in the url then i'll just send back 401 which just stands for unauthorized so let's start i'm going to go with const and i'm going to be looking for specific query string i'm going to be looking for the user my url parameter and of course we know that it is available in rec dot query like so and i'm going to say if the user exists so if it's there with any value it doesn't really matter which one or i don't know maybe if you want to make it more interesting let's go if the user equals john okay if that is the case then i'm going to go with rec.user and notice what i'm doing here i'm actually adding a property of user onto the rack object and i'll show you why it's so powerful so i'm going to go with recuser that one is equal to whatever i mean that could be a object for example and i'll say here name john again this is just for demonstration purposes and then id i don't know four or three or whatever so that's my user now i still need to call next if i won't do that then the whole setup is gonna go bananas so i'm gonna go with next here and now of course i just need to set up a response if the user or whoever is visiting doesn't provide the query string with a key of user and then value on john and in that case i'm going to go with my else and i'll say res and then let's add a status and the 401 is going to be for unauthorized and let's just say send and simply let's try to spell this sucker unauthorized let's save that one and now notice something interesting if i'm going to go for example to my home page or product again any of the routes because there is no path in my app.used check it out i have unauthorized and if i inspect and in the network tab the same deal i have 401 because i'm not authorized to access this resource i have my authorized middleware whereas say you didn't provide the query stream parameter with a key of user and more specifically you didn't provide here a value of john and since you didn't do that you cannot access the resource so now of course if we change things around and if i go with my question mark and if i say user equals john what do you know i have my home why well because now the condition is met and now we just go to next now why it is so powerful because in the authorized we add the user right so now of course not only i can check for that query string parameter but and also access this info again this is just demonstration normally what you're going to do you'll check for the json web token and then if the token exists then we communicate with database and actually get the user again this is coming up for time being we're simply hard coding these values so back in the app.js in any of the routes now i'm not going to add in all of them but just to showcase i'm gonna add for example in app items i'm gonna set up here a log and i'll look for rec and user and you'll notice something really cool where if i leave this query string parameter and if i go to api and items check it out first of all i have the items and second in console what do i see over here i see that user and that's why it's so powerful because we can add our middleware we can do some kind of functionality and now basically i'm attaching this to my request object so i have the request object and now i'm attaching this property here and now in any of my routes now of course i went with items but in any of my routes i'll have access to that user that's why middleware is so so crucial and that's why it is a big part of express applications because it truly allows us to structure our applications as lego blocks so we have this piece of functionality we have that piece of functionality and when we combine them we have this nice working express server now like i already previously mentioned middleware is all over express so just because we're done with our initial introduction doesn't mean that you're not going to see middleware you'll see it all over the place but just to complete our initial introduction i want to cover two common questions first well if we have access right now to app.use since we know how to use it are we going to add the middleware in a route and actually the answer is yes because imagine the scenario where i don't want to apply this app.use to all my routes for example i only want to check for authorized users in the api forward slash items what do i do well i simply add my authorized middleware correct so now i'll be able to access all these routes without any issues but the items want yes i'll check for that silly query string parameter and if you're wondering well how we can pass two middlewares if you would want in a single route same we just simply grab this array so we copy and paste and now of course once i hit the items not only i will log but i'll also authorize so let's go back and i'm going to take a look where in this case everything is fine i was able to access the resource since i provided the john so notice here name john id number three i also have my console log but if i were to go to just my home page like so i have the home and as you can see i don't get anything in a console i don't get my logger and i'm also not looking for any kind of authorized user so that's the first thing that i would like to cover second what are our options when it comes to middleware so far we have covered the first one our own so we can always set up our own middleware now our other two options are express so express provides quite a few built in middleware functions again in this case we don't have to worry about setting up the functionality we just need to reference the docs to see what options are provided and then of course supply those values and if you remember the express app example we used app.use and i said put the pin on this i'll explain this a little bit later if you want you can retype this but in my case i'm just going to copy this from the for express app.js and if we copy and paste and if i place it here notice so this is a app.use method now what argument the app.user is expecting it is expecting a middleware so in express we have a built in middleware by the name of static again somewhere in the express source code there is a code similar to this now of course this is silly they have way more complicated setup but hopefully you get the gist so there is a method and the only thing this method is looking for our public folder and then i already told you that it basically places all the contents of public folder as our static assets so they're publicly available so we already covered that one and now let me show you a simple example of third-party middleware now for a third-party malware we'll have to install it and one of the most popular ones i guess for the login is this morgan npm so again just go to your search engine and type morgan npm that is going to direct you to the docs i guess for the morgan and as you can see in order to install we just run npm i morgan so that's how we install the package and the syntax is following where we just go with morgan we required a morgan and then we just pass in morgan tiny now of course this one we need to set it up in our app.use so this is really optional you don't have to install it you don't have to run it but in order for me to hammer this home i will do that so let's go back i'll stop my server and remember the command was npm i and morgan okay i installed this one so now of course this package is going to be in my dependencies like so so not only i have expressed i also have the morgan and then in the app.js of course i'm going to have to require it so i'm going to go with const morgan and that is equal to require and then again i don't have to provide the path that's the module that i installed so i go with morgan and then where i have app.use and go with app.use since i would want to add to all my rows again if you want to add for specific one there's a different scenario but if you want to add for all the routes you just go with morgan and then they basically give you multiple options and the tiny one is just going to provide you the most essential data and again if you want to reference the docs please do so so i'm going to go with morgan and now i just need to spin up my app and i go with npm start now i will remove logger and authorized from my api items just because i think the terminal is getting quite busy and now of course once i navigate for example home page in a console i have get i have forward slash now this is a status code and then i have 2.8 milliseconds and that essentially just signals how long it took for the server to respond and if i were to go to localhost and forward slash about now of course i'll see that i have get request i have about the 200 and now of course time is a bit different as well so hopefully this gives you a general idea why middleware functions are so crucial and how powerful they are and yes the bigger your express applications will get most likely the more middleware functions you'll have now they could be your own ones they could be the ones that provided by the express or there's also going to be tons of third-party middleware functions not bad not bad we have general understanding how middleware works in express and now i want to cover rest of the http methods so if you remember which seems like an eternity ago we covered the cycle the request message as well as response and in request well get was by default performed by browser but of course we have other methods as well and i also provided a second slide just for these methods and here you can see rest of the methods so get is again by default set up in a browser and this allows us to read data then we have post that is for inserting data so for example if we have some kind of api orders route we can add an order so user makes an order and we just place that order on the server so of course eventually we would say that in a database then we have put if we want to update data and of course we also have one for deleting the data and before we continue let me just mention something we're not going to persist this data so yes we'll have working examples of post put and delete and hopefully i'll be able to convey my message in a manner where you understand the general setup for rest of the methods but since we haven't covered how to connect to database we won't persist this data now i could have went the file system route where essentially we are persisting this data by writing in a file but i thought it's a waste of your time because most likely you're going to work with database anyway so we might as well skip that part so once we understand how we can connect to the database what are the methods by working with data in our database then we'll have a proper example where we're persisting in as well and in order to kick things off i'm going to navigate back to my address again the previous example is going to be in the file number 10 middleware options and again we're just removing pretty much everything starting with morgan so right after app and all the way to app.listen like so now there's not going to be a home route however i'm going to go with api and people now why do i go with api people because in the data file in the data js where we had the product there's also this one people people is an array each person is an object there's an id as well as the name as you can see very simple example so with this data array i want to showcase how we can read this data how we can add for example an extra person using the post how we can modify the person as well as deleting one and now of course i want to navigate to app.js and first i want to get my people so we simply go with import i'll structure it right away and as a side note since i might make some modifications i'll use let in this case and i'll set it equal to require and then data hopefully this part is clear since we have covered it quite a few times and let's start with the one that we already know and that is going to be a get method so i'm going to go with app dot get like i said i'll purposely set up my route with a value of api and people so that's going to be my path i'll say api and then people now this is a get method and simply will return this array so rec and res and again i'm just going to go with res status let's hard code the value of 200 then let's set up our json and since i want to be kind to my users i'll send back the object i'll say that the success property is true so the request was successful and as far as data property well i'll set it equal to people so let's navigate back to our browser and we're going to go with 5000 and of course cannot get so this is going to be 404 if i just go to the homepage and instead i have a route for api and i believe the whole path was people like so so we run that and now of course i have zoomed in already massively here so let me zoom out in my browser and we should see that we're getting our object the success property is true beautiful and then of course we have the data property and in there we have the people's array so a bunch of people in here so of course that is our first http method that is the get one where effectively we read the data and like i already have mentioned probably 20 000 times that's the default method that the browser performs so when you set up a request with your browser you right away use the http verb by the name of get and that's why you can read the data all right so we're clear with get method that's how we can read there however how we can add data onto the server so how we can insert data and in order to do that we need to use a post method but it's not like i can somehow configure browser and start making post requests unfortunately that's not how it works that's why i provided a little bit of help now keep in mind one thing where after we set up a post method effectively once we take a look at two flavors of how we can set up post request we will install one more tool which is going to be crucial in our express server development which is just going to allow us to test everything much faster but since for the post i do want to show you two flavors that we can have we'll use a little bit of static data meaning there's an app that i prepared but don't worry it's not like you'll have to do that each and every time to test any of these methods and you'll see what i'm talking about in the following videos so first let's start by jogging our memory a bit we have app.use now what app.use is doing is just applies the middleware to all our routes correct and i also mentioned that we have this option of setting up a public folder now we can call whatever we would want but for this methods example i prepared a methods.public as you can see it is just a folder with index.html with javascript html some css and once we navigate there of course i'll show you how the functionality works so this is just prepared so we can test those other methods meaning more specifically the post method because we cannot simply just perform a post request from the browser so first let's set up that methods public as our public folder that's step number one so let's set it up as our static assets and in order to do that i'm just going to add first a comment and i'll say assets and then i'm going to go with app.use again remember that is our method and this is going to be a built in middleware and the name is express static so i just grab my express instance i look for the method of static and if you remember we just need to provide here a path and instead of going public or static like i showed you previously i'm just going to go with forward slash and then methods and then public because this is where i set up my static files for these examples we invoke it and now if we go to the home page we shouldn't get this error so once you invoke there it is we have a somewhat decent looking html file with two options we have this javascript option which we're going to cover second and first one is going to be a traditional form example and again the reason why we do that is because you cannot simply just configure your browser to perform a post request you either need to use a tool which we're going to install by the name of postman or insomnia here's another popular one or you need to set up basically a working application and if you take a look in the methods public we have this working application all right and once we have the basic setup in place now let's take a look at our two flavors when it comes to the post method and i want you to navigate to index html and in there you'll find pretty typical index.html file with some styling with nav as well as deform and in form we have two attributes we have action one as well as the method and as you can clearly see the value for the method is post and this action one just says where we're going to send it and notice now we have forward slash login so that means that this url this path is on our server but of course we know that in the app.js we're not handling that so for the form there's going to be one path and then for the second example when we used straight up javascript then of course there's going to be a different path for that so this is going to be the url or path where we're submitting the form and inside of the form we have label we have input so basically we have name attribute for this one we have the id as well as the autocomplete so we'll type in some kind of value and then we'll send this to forward slash login so localhost and then forward slash login and of course we also have a submit button so now let's start by taking a look what happens when we simply submit this form so go here type some kind of gibberish in my case i'm going to go with john bravely press enter and of course we do have kind of post login okay that's fine we're not expecting anything anyway right we know that there is no route that handles the post for the login but what's really interesting here is in the network tab of course i can see my request in this case this is login now this is 404 and again i'm going to repeat this 20 000 times but check out the method so method is not get method is post and then we're going to localhost 5000 and then forward slash login now what's also really interesting all the way in the bottom what do you see here you see this forum data and then we have key value pair we have name and john and if you remember when we talked about http messages i said that the body is optional so for example when we're sending a get request we're not sending a body but when we're sending a post request it's very crucial so if i want to add something onto the server of course i want to get that data i mean otherwise how i'm going to know where to add to the server doesn't that make sense i hope it does so let's go back okay i see this name and i see john and if you're not familiar basically the way it works is whatever you provide here for the name is going to be a key so for example if i'm going to set this up as testing you'll see that now when we perform the same request the same post request again with the same value different value it doesn't really matter now of course that key name is going to be testing so whatever value you provide over here that is going to be the key and of course the value is whatever you're submitting so in my case it's either peter or john okay that's out of the way so i'm going to change it back to name and now we need to understand something where the request is coming in but a we're not handling that and b we don't have the middleware that actually adds this data that the form in this case is sending to our request so let's see how we can fix the first one and we simply need to come up with a round now in this case remember we're dealing with post this is not get and we're going to go with forward slash and then log in here because of course that's what i have in my form again we go with rec and res and technically we can come up with some kind of info i can say send and i'm simply going to say post and that's it just so we can save time on typing again let's navigate back and in this case let's try susan let's send it yeah i see the post so i don't have the 400 anymore or 404 so that's cool but unfortunately i have no access at this point to whatever i'm being sent so unfortunately i cannot access that susan or john or whatever value so unfortunately i cannot add for example to my list if i wanted to now how do we add it well this is where the middleware comes in so previously we covered static assets with express static in order to get the form data we need to go with url and coded middleware so i'll add here parse form data and essentially this is just going to parse that data and add the values to rec.body so where we have a post request in the rec.body property we'll find all the info and in order to use this middleware surprise surprise we're going to use app.use and then we'll pass in express and then url encoded and then you also pass in flag where you go with extended and you set up false and if you're wondering why are we adding this extended false flag or you just want to get more info about this url in coded middleware simply let's head back to the documentation in this case we're looking for the express and notice here i have express url encoded this is a built-in middleware function in express it parses incoming requests with url and coded payloads and it is based on the body parser so in the previous versions of express you have to actually install the body parser now in this case you don't it already comes built in and as far as this extended this option allows to choose between parsing url encoded data with query string library when false meaning this is our case or the qs library when true again i wouldn't lose my sleep over this one then the common approach is using this extended and false and once we can access it then we can do some cool functionality so first let's just scroll down a bit where we have the login and first i'm just going to start by console logging rec and body let's save that one and again back to our browser again i'm going to go with susan this was 200 so everything was successful and now of course in the right dot body i also have a name and the value is susan so now we can start doing something with this data now i purposely set up two examples one is going to be for form which of course is this one and then one is for javascript now with the javascript example this is where we'll actually manipulate this people array fourth time being with login this is a separate issue we're just dealing with the form so we'll just try to make things interesting by checking for the name if the name is provided then we'll send back welcome and then pass in that name if the name is not provided so for example if the user is trying to submit the form empty for example like so we'll just send back 401 please provide credentials again please keep in mind this is just a example and i'm fully aware that we can check for empty values here on the front end again the goal of this example is to show you how to handle this on the server so i have wrecked that body okay i can see that in this case i have name but it is empty so now of course let's set up our logic first i'm going to go with const name and that one is equal to rec that body so i'm destructuring my name property and i'll just check if the name exists whatever the value that could be b that could be bobby lee not could be again taco burrito whatever you want and as you can see i'm getting quite hungry so let's go with return res dot status then let's set up a 200 which just says that we were successful and we're gonna go with send and we'll set up a template string welcome and i'm just going to access my name so if there's some value i'll send back 200 and i'll say welcome whatever is the value if not well here we're going to go with res and let's just add status here and again just for kicks i'm going to go with 401 and we're going to go with send and of course let's say please provide and credentials like so let's save this one and now we should truly see how it works in the action now i'll leave i guess the tab for now and let's just try to submit so for example if i submit with empty values i'm going to say please provide credentials and as far as my login it is 401 that's what the server is sending back however if i type in some kind of value for example anna comes to mind i have welcome and anna so that's our first flavor when it comes to post request where we use the form and again this is just front end where we come up with an action and since this index.html is on the same server we simply go with forward slash and login of course if your front-end application is separate from your server then you're going to provide a full path where the server is hosted so basically a full domain and then we go with method post now this is technically a front-end part but it is crucial that we understand it so then we perform of course a post request we hit our url so in this case we hit our forward slash login and this is the part where we handle that on a server in order to get that data whatever we are being sent we need to use a middleware this one is built into express so again we simply just need to use app.use which is going to apply this middleware to all our incoming requests and then we just pass an extended false flag and the moment we do that indirect.body will have access to our form values so whatever is set up here as a value that is going to be our key and whatever is passed into our form well of course that is going to be the actual value that we're getting so if i go here with name i'm gonna see either susan anna or whatever user provides now like i already previously mentioned this is just for demonstration this is just so we have a bit more interesting example e instead of just sending back the name so hopefully this part is clear and now we can focus on our second flavor where we use javascript to send the request all right and once we have the form set up out of the way now let's take a look at the javascript option before we do though there's one more thing that i would like to mention if you take a look at the headers you'll notice something interesting where we have a content type for the request header and of course this is going to be application and then we have this form url encoded and the reason why i'm showing that because of course for javascript it is going to be a bit different so just keep this one for your reference now let's navigate back to our static files basically to our front end and now let's take a look at the javascript approach and interestingly here where i have the javascript i do have the form keep in mind we'll still handle this form but in this case it's going to be done strictly using javascript and we'll use javascript to send our http requests and that is very very crucial that is going to be the difference where instead of form now i'll be sending that request using javascript and of course the content type will be different that's why i showed you the form example but what you'll also notice that right away we have our list and if you don't believe me you can double check in data we have john peter susan anna and emma so what's happening well let's go to javascript html this is where we have our frontend logic and again let's take a look at our index html a little bit of css nav and then we have the form now in this case i don't have the action and i don't have the method okay interesting so i have name attribute it still has a value of name so i should expect probably that this is going to be the value that's coming in with my request then i have a little bit of form alert this is where we'll display a little bit of functionality as well as the result now if you're not familiar there's a package called axios which essentially just makes it easier to set up http requests so instead of using the built-in fetch which i could have used i think axios provides a cleaner api and better error messages and since i don't want to spend three hours on explaining all this code i simply went with axios and the way i set it up i just set up the cdn link so this just gets me the axios library and then the moment i install it of course i have axios in my front-end project please keep that in mind those are two separate things this is a front-end project and in order not to confuse you more i just set up a few script tags instead of going with a separate javascript font so as you can see here i'm selecting the result so that is my div and i have this fetch people so that is the function that fetches people from my server now notice the path it is api and people why well because in my server i have also api people so this is for get requests that's the default one however in this case we're not doing that with a browser we're doing with javascript so axios has the method by the name of surprise surprise get that just means that on the front end we're performing a get request to the same server that's why we go forward slash api and then people so make sure these urls match so if these paths won't match then you'll have an error and to showcase that if i go with p poles then if you navigate to the front end and if you refresh can't fetch data so we try to fetch people from our server then we do a little bit of logic and this is just vanilla.js not going to cover it basically we tear it over and then we just set up a nice heading 5s and all that and then we invoke the function but if there is an error we'll look for the error property now in this case i'm not the structuring it i'm actually not using it i just say can't fetch data so that's step number one now the second one is of course using the form so then i select the submit button i select the form i also select the alert because we will display an alert if the value is empty and again let me repeat i'm fully aware that we can check for that in the front end i just wanted to showcase the server setup and then notice something interesting where i have this try and catch block in my functionality so the moment the user is submitting the form of course i invoke my callback function it is a sync because for the actuators i can wait for response and notice this one so i have axios and again surprise surprise the method name is post why because we are sending a post request and this is just an axiorys thing but again we provide the value in this case the url value is api and people so something that we're not handling yet on our server and this is the value so again this is just axio syntax where in order to set up whatever data you're sending you just pass it as a second argument and you set it up as a key value pair now what's really cool that would axios they set up all the content types and all that good stuff for you so again you just save a little bit of time now if there is an error in our case that is going to be if we're trying to submit something and in fact there's no value meaning we just try to submit empty form value then we will display the error message and again this is really cool because axiorys just provides a very useful error api unlike the fetch where you really need to jump through the hoops so let me save it back to people so we can see of course all the people that we have in our array currently and then of course we'll focus on this post one so as you can see i get the input value and i just passed it in as a name property awesome so now back in our app js of course we need to handle it and please keep in mind one thing where app dot post and then api and people is not the same as api get and api people even though the url is the same methods are different and that goes for all the methods we're going to use whether you're talking about put delete or whatever so just because the urls are the same doesn't mean that they mean the same thing no the method is different here i'm just reading the data i'm reading data from api people here i'm actually trying to add data and again we're going to go with wreck and res and let's just go with some simple response now for time being i'm just going to say that my response is going to be 201 now that's the response that we send back if we are performing a post request and we are successful so i'll just say res that status 201 and for time being let's just say send and i'm just gonna say success and of course now what i would want is to navigate back to my javascript one hour fresh i'm getting all my people and now let's try it out so i'm gonna send this one so i sent again here nothing changed but if i take a look at my network tab i should see and by the way sorry i'll have to do that one more time let's go with i don't know susan here let's try to submit and there it is now of course i have api people and 201 so that's the response that i'm getting on my front end so let's bravely click on this one and we can see that the request url is api people okay the method was post now the response was 201 so it was successfully created and now check it out when we look at the request headers of course we have application json so on our front end we do need to add this content type when we are sending the data now again what's really cool about axios it adds for us but in general you need to keep that in mind and there it is again we have this request payload and the name is equal to susan so whatever i'm going to pass it in if i'm going to send it empty then i'm going to still have the key name and the value will be empty now the gotcha here is even though we're handling a form submissions we're not handling the json data so yes we know how we can send back the json data but we're not handling the incoming json data and this is where another middleware comes into play so i'm going to say parse json here and we simply need to go again with app.use and we go with express and json now in this case i'm not going to go to documentation if you want you can do that in my case i will try to save us a little bit of time and we'll skip that and here we have api people and now similarly to our login we have access to the form data that is being sent with javascript in the rec dot body previously before this was added no we have no access yes when it comes to form that was one setup now when it comes to straight up http requests for example in this case sent with javascript no we had no access so we were getting a json and now we added a specific middleware that handles that so of course in this case now we can set up more logic correct we can say that we're looking for the name and if the name is provided then awesome then i'm going to send back that new person that was created so we can add it to our front end and again this is the case where we're not persisting this data anywhere later we'll learn how to do that for now i already have the code that adds it to our front end however if the user tries to submit without any values well then there's going to be a error message so in the api people in the post method let's set up our logic where i'm going to go with const name is equal to rec.body the middleware makes it possible now and then i'm going to say if the name is not provided well then i'm going to send back the 400 then i'm going to say please provide name value so there's going to be a error message so i'll say here if and exclamation point and if the name is not provided then let's go to return res dot status and for the request error we go with 400 that's the status code and then let's go again with json and in this case we're gonna go with success now this success will be false and then we're going to go with message again i would suggest using the same properties because of course i'm handling them on the front end as well so in here i'll say please provide name value like so now if the value is provided whatever it is then of course we can send back res.status 201. hey guys it's john from the future with a small update as you'll see in a second while i was recording i forgot to change the methods so instead of writing json i just left it as send and while we can get away with it in this example normally you always want to use json instead so make sure you change your method from send to json and in this case let's just set up a proper object we'll say success is true so now we're being successful and i'm just gonna send back that person now i'm going to set it up with person key and the value will be named whatever i'm getting again please use the same ones if you want to have a same result now let's navigate back we can refresh just so we are all on the same page and if we type susan now we should see another susan added to our list and then again we can go with john and i'm just being lazy on coming up with original names and as you can see every time we add value in our form we're being successful we're actually getting back this value from our server and then we dynamically added to our front end and again the reason why we're doing this way is because we're not persisting this data so that's why the setup is following later of course we'll learn how to persist this in a database as well and if i try to submit with empty value check it out now of course i have people and this one is what 400 right notice here and it says please provide name value now if you want to do a bit of console logging you're welcome to do that on the front end if for example you are iffy about the syntax but just to let you know when we talk about axios here effectively we're getting back the whole thing so when we perform a request http request with axiorys we're actually getting back a giant object now what we're interested in that object is a data property so that's the response that is coming back from the server and then in here as you can see i set up a heading 5 with data.person so that's the person that we're sending back from our server now if for example there is an error we go with error response again data property because that's where the useful information sits because the object of course is giant with lots of useful information but as far as what we're sending back it is sending in data and then message now i'm looking for the message property of course here because i set up a message property on the server hopefully it is clear this is our second flavor where effectively we perform a post request from the application and of course in that case we do need to provide content type as well as the data and next video we'll install and cover some basic setup for a very useful tool that is going to save us a lot of trouble when we work with post delete as well as put methods all right so at this point we're familiar with two ways how we can send a post request so we covered how we can do that using the form as well as straight up http request in our case using javascript however there's a major problem in our current setup and the problem here is following if we need to create a frontend to test something for every route as you can see i mean our development is going to be extremely slow because we can clearly see that it's probably going to take us way longer just to set up a front end than setting up just one simple route so every time i create a route i'm probably going to spend i don't know five six times more on setting up the front end where i can test this route and of course there has to be a better option and that better option is a tool called postman and postman is just awesome for quickly testing our apis so at this point i strongly suggest that you navigate to postman.com again it's a free tool so you're not going to have to pay anything but for mainer of the course yes we'll use this so if you're kind of iffy about installing something new this is something that is required so navigate to postman.com and then they'll try to sign you up you don't have to do that just keep scrolling down keep scrolling down and all the way in the bottom you'll see this download app option go here and they'll right away detect which operating system you're using of course in my case that is mac so download the application once it's on my computer i'm going to navigate back to the desktop i'm going to go to downloads i'll crack it open then of course i'll just move it to my applications like so and i already had one on my computer but i removed it so we can do these steps together then this is the application let me zoom in that's the postman so just click on it and then it's going to spin up the app and eventually you'll hit the dashboard and i'm not going to spend half an hour on this setup but of course as we're progressing we the course as we're progressing with our examples we will cover more features that this app provides and basically here you'll have all your requests that you can actually group in collections and again that's something that we'll cover a bit later and this is where we can make those requests and in order to create a new request we just click on this plus sign and check it out so at the moment i have untitled a request in here i need to enter the url and i can send my request not orders here on left hand side what do i have i have get but what's really cool i have all these methods available as well so first let's test out the get route and then we'll see how we can deal with post route as well now as far as our url what it is well it is localhost 5000 and of course the full url is api and people now this is for the post as well as the get and since we're testing it of course that's why we have a method with the value of get so let's go here local host and then five thousand then forward slash api and people and the moment i click send check it out what do i see here in the bottom i see my object the success value is true and there i have my data so as you can see the moment i create my route for example post route or put route or whatever i can test it immediately i can test it within a few seconds instead of building the whole front end just so i can test one route and of course once we have covered get route now let's see how we can deal with a post route so we need to change the method of course now the url still stays the same because i do have a route for the post as you can see and in here what i'm looking for i'm looking for the name in the body and how do we construct a post request in a postman well we do that in a following way first we go to the body and we look for raw and instead of text i go with json because i'm going to be sending a json data so this is not the case where we're working with the forms in this case we're sending a json data and what you'll notice something really interesting in headers right away there's going to be a content type so let's see let's set up first the body and you'll see how it gets added so we're gonna go here with a name again this is what i'm looking for that's why i need to pass it and then i'm gonna set up some kind of value now since i'm setting up the json please remember that we need to use double quotation marks so i'm going to go here with john and if you paid attention previously we had eight headers and now we have nine so i'm gonna go back and there it is now i have content type application json so that's really cool we don't have to do anything the header gets added for us and of course the moment i click send check it out now i have success true and person john why do i have that well because that is my response i have success true and of course whatever name i received i just sent it back so now of course let's quickly test out our 400 as well so i'm going to navigate back and then in the body i'm just going to send a empty string or you can remove name altogether that's really up to you and now of course i have 400 bad requests and success is false and of course i can see the message so as you can see we can test it within seconds and to really hammer this home why don't we create another post route and quickly set up some kind of response and let's test it out in our postman as well so i'm going to go in between the post and login i'm just going to go with app.post and the route is going to be following i'm going to go with path of api people people and i'm going to add a postman here or you know what let's do it this way let's go postman and then people like so and then as far as the callback function again we get rec res and then in the body again i'm going to be looking for the name property so i want to get that name so i'm going to say that i'm expecting it we'll go with name rec dot body again if you want to cancel log the body you can do so but i think we have done that quite a few times so i'm going to omit that then i'll copy and paste my response so again if the name is not provided meaning if the property is not there or if it's just empty i'm sending back to 400 however if i'm successful then i'm just going to take my array i'll add that extra person and i'll send it back now i'm not going to add the id i'll leave that one blank because eventually database will do that for us so i don't really see the point of doing that manually so i'm going to go back to my api postman people and then again this is my error response and now let's copy and paste our status and then instead of sending that one person we created why don't we do this why don't we go with data and then of course the array name is people and now as you can see i'm using the spread operator and i'm just going to add that one single person so i'll save now of course we do need to change the route so it's not going to be api it's going to be postman and then people like so now let's add for example peter and the moment i click send there it is i have my success true and as far as data all the way somewhere should be peter as well so again we just grabbed that peter and then we added to our array hopefully this makes sense and now of course we can work on other http methods as well all right and once we're familiar with postman now let's work on the other two methods so now we're gonna be working on put method as well as the delete so i'm gonna scroll down and below the post login route i'm gonna go with app and then put now again this method is for editing the data so put method is for update and again the convention is following where if we have a list for example in this case that would be api and orders if we want to edit or delete we go with our route parameter where effectively we set up a route for api orders and then we go with colon id and this is going to get me that one specific item now please keep in mind one thing where this is a convention so technically there are multiple other ways how you can set it up but there's a reason why that convention exists and that's why throughout the course we'll stick with this convention i'll cover the official name of this convention a little bit later as well as a bit more details about it for now i just quickly want to cover both of the methods so i'm going to navigate back i have my put method that is for modifying the data and in our case what is the url for the whole list because that is api people so this was just for testing correct and then we go with api forward slash and then we go with people and then of course i also want to add that id so this is going to get me that one specific item and again the reason why we're doing that because when we'll send our put or delete requests we'll send to a specific path so this is going to be that one item and if that item exists then in the body there's going to be data to update or in the case of delete there's going to be nothing in the body we'll just remove that item and you'll see how it works in a second so please be patient so we're going to go with people and then remember again we have route params and in this case i'm not going to call this person id i'm just going to say id just remember that we can call it technically whatever we would want and now in this case there's two things that i'm looking for first i want to get the value here in the params and remember we access that using the rec params and the second thing when it comes to update when it comes to the put request i'm also going to send something in the body why well because if i'm updating for example if i'm changing the name from peter to susan or whatever of course i also need to supply this value so you need to understand that there's two sides of this request not only we're looking for that specific item that's why we use the params that's why i specifically say hey i would like to get the item number one or item number two i also need to supply this value because otherwise what's the point of updating something so let's access both of those things let's say that i'm gonna get the id from rec params so this is going to tell me which item and then the second thing since of course i want to update that item i need that value as well correct so we're going to go here with const and i'm going to be again looking for the name and we'll say reg dot body and that's it that should do it so these are the two values that we're gonna get from our question and just to make things interesting i will console log them right now so i'm gonna go back to the postman and remember we need to change the url it's not gonna be api postman in this case it is going to be people and now you can select any of the ids whether that's one all the way up to the five so we go here with one and then as far as the value what is the value for the first one it is john so kind of makes sense if i'm updating that i go with peter correct so we have put request we have api and then people and then check it out the moment we send it now of course the request is hanging don't worry about that but in a console we should get api people and then the id and of course the reason why i don't see anything because i was smart enough and i didn't console log anything so i'm gonna go back with id name and you know what for timing let me just send back hello world okay let's go here let's actually send it one more time as you can see could not get the response that was the error this time in this case i am getting hello world so that worked beautifully and as you can see the status code is 200 as well and then in the console i have one and i have the repeater so this is going to be the id and of course this is going to be the value now if i'll change it of course if i'll say number two and if i'll send it again i get back my response and now the value for the id is due hopefully this makes sense so now of course at this point we need to set up the logic again we are going to set up the logic with our local data with our people array eventually in next examples we'll work actually with database but the main idea is exactly the same where from the postman while we're testing we're sending the id in the url basically we add that url parameter and then in the body we'll send the value so that part won't change just the functionality in here and as far as this functionality well since we have a simple javascript array first i would just want to get the person with that id if the person doesn't exist then i'll send back the error response and if the id does exist then i'll just change the value now i'm not going to be looking for the error message if the value is not provided we're going to cover that once actually we work with database i think is just going to be at the moment waste of our time so let's do it people i'm going to remove both of these console logs hopefully you understand how we supply both values in the postman and i'm going to start by creating a person and this is going to be equal to people dot find again i have the array so i have access to all the array methods and then if the person id matches to my params id then of course i'm going to get the person now let me check in the data notice i still have it as a number so i'll have to change the type as well so i'll say if person id is equal to a number and i'll pass in the id that i'm getting from my params whether that's one five or maybe it's going to be id that doesn't make sense all right good and if the person doesn't exist well then i'll send back the response now again in order to save us a little bit of time i'll scroll up and i'll look for any of my error messages since i just want to copy and paste and change some values around so in this case i'm going to look for this name if it doesn't exist then of course we have the error and in our case of course we just need to change it around if the person doesn't exist so if we cannot find that in the array then we're sending back 404 remember that was the status code if we cannot find the resource and as far as the response we have success and of course it's going to be false and now let's go with message and in the message we're going to use a template string we'll say no person with id and then i'm just going to pass in the id so that's the first response if of course the person doesn't exist so if in the primes we enter for example value six we know that we have only one to five or abc now the second thing if the person doesn't exist now of course i just want to iterate over the array and for that specific person for the person whose id matches my params value i'll change the name since i'm expecting that one to be in the body again we're not going to deal with this error for now we'll do that once we work with database and we're going to go with new people new people here and we'll say people map so i'm iterating over my array again i'll reference each and every person as a person and i'll say if person id matches to that one i have in params so number id again then i'm going to say person name since that is the only other property i have is equal to my name now where i'm getting the name because i'm getting it from the body so if the id of the person matches to that one in the params then please change the name that i can find in the body if not then simply return a person return a person and now of course all the way in the bottom i'm going to go with res dot status and then we're sending back 200 since the request was successful as far as the json we go with success or sorry not super we're gonna go with success true and then as far as data well now i'm sending back the new people so let's go back at this point i have two so let me change it back to 1 because i know for sure the first value was john so again the path is api people and then id of 1 and i just want to change it from john to peter so let me double check in data this should be john uh it's a good thing i didn't go with the idf2 since that one is already peter so now let me send it and check it out now i have success true and data of course is my array and instead of name being john for the person number one now the name is peter and of course if i'll do the same thing for example for the person number three again we send it back of course now i have three peters because i just keep changing those values again we're not persisting that data but while we're making requests you can clearly see how we are modifying this data and we do that using http put method and then of course the path is api people and then whatever the id and again the whole reason why is that happening because on our server we are handling that all right and the last method i would like to cover is a delete method so below the put method below the modify option i'm going to go with app and the method name is delete again the convention if you have a list is going with a list url and then add that specific id because the setup is going to be extremely similar to a put one now the only difference is going to be that of course in this case when we're deleting we're not expecting anything in the body the user hits the url for example api people and then one we just remove that sucker from our list that's it so let's go down where we have app delete and again the path is following where we go with api and then people and again let me stress one more time something where these routes are different when we talk about app.get and api people when we talk about app.post and api people or even if we talk about app.put and app.delete just because the path is the same since the method is different these are different requests that is crucial please don't think that just because you have a different method you have to set up a whole new path no you can have the same value for the path if the method is different that is totally different request so let's go here again with our callback function we should already be comfortable with this one we have rack and res and in this case i'm not gonna the structure out the id from the prompts i just want to showcase that we also have this option of accessing the params directly so first again i want to look for the person then we'll send back this response and yes oftentimes put and delete are going to be extremely similar and then if the person does exist then of course i'll just filter out the array and remove that person from the array since again the whole point of this request is to remove that person from the array so in this case you can actually copy and paste and i know that some of you might find that annoying but at the same time we do need to speed this up and start working with a database so hopefully you can forgive me i'm just gonna grab everything starting with the person all the way until the end of our error response d404 let's scroll down copy and paste and this is what we're trying to do so i'm trying to find a person whose id matches that in the params and of course in this case i haven't destructured out the id right so i just need to change this around where i go with rack and then params and the id again the setup is exactly the same the difference is that i'm directly accessing the params object and if the person doesn't exist then we send back d404 so let's try this response i'm gonna go back to my postman again the api is people but we need to change the method right so now i would want to delete and since i want to test out the error and as a sign up you can send the body doesn't really matter we're not handling that on server anyway so it's really irrelevant but since i want to test out the error i'm going to go with abc so again the path is localhost api people and then abc and if everything is correct i should see the error and of course there is but something tells me that this is a different error so let's go back and check it out and of course the issue is following notice here in the json how i'm accessing the id now of course i haven't destructured it right in this case i went with rec params and then the id so i'm going to go with rack params and the id let's save it and let's try one more time again i'm looking for a person whose id doesn't exist so i'm gonna get the error and there it is i have success false and as far as the message no person with id of abc so i was looking for the person with id that's not in my array so that's why of course i got back the error response so now i'm gonna go back to our app delete request and here i just want to filter out the array and the way we're going to do that i'm going to go with const new people is equal to people.filter that's my array and i'm just filtering it i'll pass in my callback function and i'll reference each object with the person parameter and i'll just say if person id does not match the id found in rec dot params then return that person if it does match then it's not going to be included that's why we go with exclamation point and remember that we still get our id as a string so we must do the number one first and then only we go with params and the id so that's our new array without that specific person whose id matched the one in params so now of course let's just go with our return return res dot status here and this is going to be 200 of course and i'm going to go with json and we'll set up our object success is true and i'll send back the new people array so we're going to go with data and then new people let's save it and let me test that out e in the postman where of course now i'm gonna go with id that is in the array and that's gonna be number one so if i send notice how it is irrelevant if i send body again because i'm not handling that on the server anyway but if i take a look at my data well the person with id number one john is missing why well because his id matched to the one that i passed in the primes so now of course he was removed from the array so if i'll go with five same deal now the john is back here because again we're not persisting data but the person with id of five has been removed from the array hopefully this gives you a good understanding how we use other methods as well not just get and why we go with postman instead of setting up the front-end but before we cover router in express let me just stress something that yes while we're developing our server of course we'll use postman because you can clearly see how much faster it is i set up the route and i quickly tested otherwise if i would have to build a front end for every route that i'm creating i mean the process would be just very very long but at the end of the day when you set up the api the expectation is that there is going to be someone who's using that data now that could be on your own server so for example if you're building a full stack application with mern that's one of the options that could be decoupled application remember how i showed you a example where i have the api on my server but then there is a react application that uses it it doesn't mean that you have to build that front-end application yourself just be mindful that the whole idea of setting up the api is that someone is going to be using that data that's it that's all i want to say and now of course we can talk about router in express all right i think we're moving along quite nicely but as you can see the moment we're starting to have more routes and more functionality we have another issue and that issue of course is the fact that our app.js is getting quite busy and technically we don't even have that many routes so what is the solution well the solution is using express router where we can group those routes together and then as far as the functionality and actually set them up as separate controllers now eventually in the next example when we work with database i'll cover again the common setup which is called mvc basically it is a pattern it's not a rule but it is a nicely used pattern when you're setting up the api but we are missing the model part in the mvc pattern because we haven't connected the database so i'll just leave it at that just please keep in mind whatever i'm about to show you in this video and in the next yes it is a pretty common convention and pattern so i also suggest sticking to that now also i want to mention that in this video we will do a bit of copy and pasting meaning we'll have to refactor the code because i think this is a perfect example for us to set up the router where we already have some code so you can clearly see the benefits of setting up the router instead of me coming up with some empty routes and then saying that yes that is the best pattern so with that said first where we have the request the post request for api postman people i want you to change this around a little bit so as you can see i keep going back and forth in this case i want to go with api people and then let's just say postman again it doesn't really matter we're not going to make requests anymore from the postman in these examples anyway this is just about our code structure and then once we change this around i also want to move this login up just so it's a bit clearer what we're doing so take this login route and keep moving moving moving moving and just place it on top of your routes and there it is now of course i have my login and now notice the pattern whereas i have one route for the login but then rest of them i have api people api people api people postman api people id and hopefully you get the gist again i have api people id so wouldn't it be nicer if i could somehow group all the api people and also add one for the login but basically in a separate file and the way we can do that is by setting up the router now again common convention is just creating another folder so i just want to make sure that i'm actually doing that in the express tutorial let's create a new folder and common convention is calling this route and then you just come up with whatever name you want now in my case i'm gonna go off for the login because we're just gonna imagine that maybe there's going to be one for register one for logout or whatever and then there's going to be one 40 people so that's going to be for my api and people so let's set up these two files i will zoom in massively just so you don't think that i'm cheating so let's go here with alt js this is where i'll place my login one and also right away set up my people people just okay awesome i'll start working in people.js because it's going to be a bit interesting and then we'll do the same thing in the auth as well and the way we set this up we simply start by requiring the express so we go here express require and of course the module name is express and then instead of setting up the app we go with router and we explicitly get the router from the express so this is going to be a router instance that takes care of the routing instead of the app so we're not going to do the routing anymore in our app.js well sort of we will we'll use the middleware but as far as the specific urls we'll handle that in this routes people file and the way we set up the router we go with router and that one is equal to like i said express dot and then we go with capital letter router and then we invoke it awesome that's a great start we can save this sucker and now i want you to go back to app.js and don't grab the login that's why i set it up separately above all the routes but grab all of the ones with api and people so take these suckers here all the way up to delete basically stop at listen cut it out and then copy and paste in people like so okay great so now of course i have all my routes here now our next step is actually changing from app to router because i want the router to handle the routing so in my case i'm going to select all of my apps like so so i'm just doing that with command d in the visual studio code and at this point i should have multiple cursors like so and i'll set up my router and now all the way in the bottom i want to go with module not exports and of course at the moment i'm exporting my router and then once we export a router of course in the app.js i want to set up a app.use where i'll say yes for the path that starts with api and people i want to use my people router and the way it's going to look like we're going to go back and at this point we have people here and as a side note actually we need to cut it out but we're not going to use it here as well eventually the setup is going to be different so for now yes please cut it out and copy and paste in people but since we'll be setting up the controls we'll have to do that one more time anyway so i guess i'm going to go below the router i'm going to look for my people otherwise my functionality won't make sense and in this case remember we are sitting already in routes so i need to go two levels up and i still need to look for my data correct so now of course our functionality should work hopefully we don't have some weird bugs and then like i said in the app jess now of course i would want to use my app.use so i'm going to go below express json and i'm going to say app.use and now i need to set up that base route now what is my base route here well it is api and people correct because this is just my route and then in some cases i have the postman or i have the id that's it but the base stays the same okay awesome so we provide this path we say api and then people and now i want to set up that router and of course in order to set up the router i need to import it and you can call it people router you can just call it people again that is really up to you i'm just going to say people is equal and now we need to require it and remember we have a folder by the name of what routes and then we also have people file okay awesome we require our router here correct so that's our router and we're exporting awesome so we get the people and like i said with use we can use the path if we want so this is not going to be applied to all of them this is only going to be applied to the ones that start with api people and then we pass in the people we'll save it but there is a problem you see once we set up this router with a base path in the people actually we have a mess right now because we already have the base for our router in app js where we have api people and now in the people.js if you check it out we actually have api people forward slash api people so i fully understand that this is going to look a bit drastic but in order for this to work we actually remove everything we remove that base so we go here with just a forward slash why well because we already have the base here we have api people so that's how the route is going to start and then we just have the forward slash so this will match whatever i have in the address and since in the get and in a post both of them just have api people well i simply go with forward slash again i fully understand that this might look a bit confusing in the beginning but again the more routers you'll set up the easier it's going to get so this will just match whatever path i have here whatever base path i set up in my app.js so i'm just saying yes i'm using this people router and in the people since i already have base path in place i can simply reference it using the forward slash so this is going to match whatever i have in app and once i have spent what seems like an eternity on the base path i can keep on scrolling and again notice i have api people and then postman so what's the only thing that i need here it's just a postman because i already have api people so i remove this sucker here keep on scrolling then the same with id right we only care about this one that's the whole point of setting up the router so we can start splitting up our functionality in multiple files same goes with this last id and even though i think i said that we're not going to use the postman i do want to quickly check and i'm going to go with get simple if the get works trust me the other ones work as well so we go here with api people we send but unfortunately i get the error hmm that's interesting so let me check i think the problem here is in the app.js i don't have the forward slash so let me try this one let me send it one more time and there it is now of course everything works so my apologies i forgot to add here forward slash that's why we were getting the error and of course everything works i can go with get i can get my list if i want i can also maybe delete a person so i'm going to go delete and we're gonna test three so let's see we send and as you can see the person with id of three is missing so as you can see our route works so that's the first step so now here's the challenge try to repeat the same thing with login now with login it is going to be a bit simpler because we don't have that long of a path but again stop the video and try to set up the login yourself and then once you're ready resume it and we're going to do it together how was it hopefully you were successful and i'm going to give it a shot so first remember we needed a file so in this case i do have auth js awesome so i'm just gonna cut this sucker out from my app.js and place it in off then of course i do need to have the boilerplate for the router so again let's go with express require we require the module by the name of express of course then we set up our router router and that one is equal to express dot router we invoke it then we change this value around like so and then we're just gonna go with module and then export and that one is equal to our router we do this then we navigate back to app.js and we'll have to import it as well so we go with auth i guess let's call it that and we're looking for auth file that's where our router is coming in and then of course i just need to set up my middleware myapp.use where i provide a path of what well of login and in this case i'm going to be more careful and i will add the forward slash and of course i'll set it up as auth so let's save this one and then the only thing we need to do in the login is simply change it around where i'm already handling the login in the app.js so forward slash login so again my route now is forward slash login so i simply go with the forward slash i already covered the route in the objects so i don't need to do that anymore in here and you know for this sucker just to make things a bit more interesting why don't we use the browser now keep in mind you can still use the postman if you want but i'm gonna go the browser out so we're gonna go with new window i'm gonna go with 5 000 here and of course this is going to be the small screen i have traditional form so let's go with some kind of name peter and i send and i have welcome peter and of course if that is the case i know that my functionality works so we are in good shape again probably the most confusing thing is this one where we use app.use to set up our route so all the routes that will start with this api people are going to be located in the people.js in the routes folder and in there instead of using app we use the router and then since we already have the base setup in the app.js when we have a route that exactly matches the base we just go with forward slash now if there is something else after the base route so some additional info of course then we go with forward slash which just means that we match the base path and then we add whatever value we want and hopefully you can see how much cleaner is our app.js where now we're splitting up the functionality in separate files for our routes beautiful i think we really clean up our app js but we're not out of the woods yet if we take a look at our auth js yeah this one looks somewhat clean but we need to keep in mind that we only have one request we only have one post request to our login however if we take a look at our people.js it is still somewhat of a mess because we have a bunch of functionality since of course we have more routes and of course a better setup is if we would be able to split this up into a separate file and i'm talking about the functions so imagine this scenario where we only would have a router then i'm gonna set up my method whether that's get post or whatever then i'm still gonna have the route but the functionality this one the controller is going to be in a separate file so it's going to be a separate function and you'll see how much cleaner our file is going to look like just in a second so again we need to head back to our express tutorial now i'll zoom in i'll create a new folder and again common convention is calling this controllers for the reason that there is a pattern called mvc so model view controller and then again we come up with the name in my case i'm going to go with jobs or i'm sorry not jobs i'm going to go with people and i'm not gonna set up one for the other one for the auth since there's only one but for people i will set up a controllers file by the name of people.js and here i just to set up first my functions and the way it's going to work we're going to go with const and then again you just need to come up with a name so for example for get request where i'm getting people i'm just going to call this get people keep in mind this is just a function so the name is really up to you and since i'm going to have the same functionality of course i need to keep in mind that i do need to have access to rack and res now it's really cool that once i pass this function as a reference it's still going to work so i simply go here with this rack res and set up the functionality now probably faster is just going to be doing like this where i cut out and then back into controllers i copy and paste now i know that some people might find this annoying but yes i'm purposely refactoring the code so you can see the benefits right away and i'm going to do that for all the functions and for a little bit it's gonna probably look messy where i'm gonna do the same thing for the post so i guess first i'm just gonna cut it out and then back in the controllers nothing routes in the controllers let's come up with that function as well so const and in this case i'm going to call this create person i'll copy and paste the code okay awesome back in the routes let's get the postman one so in a controller let's also call this const and create person and postman like so copy and paste that's my function then back in routes i have one for put so i think it would make sense if i call this for example update person again cut out everything starting with a function and then all the way to the closing parenthesis cut it out back in controllers we're going to call it const update person like so copy and paste and lastly let's deal with a delete one as well so let's keep scrolling again we cut everything out like so and then back in the controller let's create one for deleting the person so const cons delete person and copy and paste and if you remember which seems like an eternity go when we covered the exports i said that of course we can also use right away module exports and then whatever so for example in this case that could be get people or create person or create person postman now in my case i always prefer to do my exports all the way on the bottom where i say module exports now this is going to be the object and now i just want to access all the functions keep in mind it doesn't change the functionality functionality is the same where i'm basically exporting an object with bunch of functions so here i just need to reference their names so it's get people it is create person create person postman then update person and lastly it is also for deleting the person now one thing that is missing of course is the people like i said this is just going to be temporary so i'm going to go to the controller here and i'll copy and paste now in this case the path is correct because the route was already in a separate folder so that should still work and of course now i can save my controllers and in the routes what i need to do is of course import all of them so in this case we go with const and again i'll write away the structure all of them so let me just copy and paste i think it's going to be faster like so since the names of course are going to be exactly the same i destructure them and i'd structure them from require and then of course we're looking for controllers and then more specifically i'm looking for the people like so and once we have required them of course now we pass in the function reference so for example here i can say get people now i do need to add a comma and if everything is correct our functionality is still going to work so in the controllers we're still accessing rack and arrays and we're still sending back the response but of course the benefit of all of this work is the fact that our routes file is gonna get much cleaner so in here remember the name was create person like so and then we have one for create person postman and let's set it up like so then we have also one for update person and lastly we have one for the leading person right so we go here with delete person i save again i'm not gonna test all of them out but i'm gonna go with for example delete and i'm gonna look for four this still works i remove the person number four and also if i check out the get one for the people this also should get me back the array so i know that my functionality still works but i nicely cleaned out my file now lastly before we talk about the databases i just want to mention that when it comes to setting up the routes we actually have two flavors so i'm gonna comment these ones out and i'll show you another way how we can set up the routes and effectively the benefit is that we can set it up in fewer lines of code keep in mind the functionality is going to be exactly the same so again this is going to be the case where it comes down to your preference if you prefer setting up your routes this way you can definitely do so there's no rule against it if you prefer the method that i'm about to show you then of course you can use that one instead so we go with a router and then we go with route and then in the route i set up the path and again since there's get and post that match exactly what i have in base same situation i just set up the forward slash and instead of setting up them separately for example get and post i can just chain them so chain one after another so i go with get that is of course my method that is not changing and then i need to pass in my controller function okay as you can see almost the same in this case however i can change it now the method names did not change the paths did not change they're still actually referencing the base path in here what we have in app.js but since we can chain it we can simply write it in one line of code so of course the callback function is gonna be create and i believe it was person so create and person like so then we have of course one for the postman so in this case of course it's not going to change it's pretty much going to be the same logic where we go the router route like so and then we go with forward slash postman and then of course i want to chain dot and i believe it was post right and then we go with create person postman and then we can again set up one line of code for the put and delete so in this case i think i'm going to just copy where i have router dot route then we set up our route and in this case it is going to be forward slash and then id and then we have two we have one for put and we have one for delete so we go with delete and then as far as the callback functions we go with update person and also we have delete person and finally let me just stress it one more time where whichever setup you choose is really up to your preference functionality is exactly the same we go with router route and then we can just chain our methods and add the callback functions now in this case we set up each route separately so for example if you have multiple urls that match yeah you're in good shape you can just set up router route pass in the url and then chain all the methods and lastly let me just quickly test it one more time since i made some changes i send it and there it is i successfully get back my people so with this in place with our router in place with the fact that we have covered all the methods the get post put and delete i think we're ready for the next level where we connect our server