Express.js Tutorial Series

Introduction

• Presenter: Ansen
• Purpose: Learn Express.js in 2022 through a new series of tutorials.
• Previous Content: Tutorial on Express.js made roughly two years ago.

What is Express.js?

• Definition: A web framework for building server-side applications.
• **Uses: **
  • Building APIs for clients
  • Performing server-side tasks such as saving data to a database
  • Scheduling cron jobs
  • Building real-time applications (e.g., with Socket.io)
  • Versatile; can be used for literally anything on the server side

Typical Uses in Web Applications

• Creating/Persisting Users
• Keeping track of user invoices
• Performing tasks that need to be executed server-side
• Easier server-side application building with Express.js

Tutorial Series Content

• Start from basics
• Setting up a simple Express app
• Basics of GET and POST requests
• How to:
  • Retrieve data from Express application
  • Create data with Express application
  • Connect to databases (MySQL and MongoDB)
  • Use an ORM (Object Relational Mapper)
• Advanced topics:
  • Sessions
  • Authentication
  • More complex concepts

Prerequisites

• Basic knowledge of JavaScript
• Familiarity with Node.js
• Have Node.js installed
  • Download: nodejs.org
  • Current Version Used: 16.13.1 (or newer)
• Text editor (e.g., Visual Studio Code)
• HTTP Client (e.g., Postman)
  • Alternative: Any other HTTP client

Setting Up the Project

• Terminal Setup: Windows PowerShell (or Terminal/iTerm for Mac/Linux)
• Steps:
  1. Create a new directory: express-js-tutorial
  2. Navigate into the directory: cd express-js-tutorial
  3. Initialize npm: npm init -y
  4. Install Express.js: npm i express
  5. Open Visual Studio Code: code .

Optional but Recommended

• Install nodemon locally:
  • Ensures nodemon runs locally even if not installed globally
  • Sets up some scripts for development

Project Structure

• Create a src folder
• Create index.js in src
• Update package.json with scripts: "scripts": { "start": "node src/index.js", "start:dev": "nodemon src/index.js" }
• Purpose of nodemon:
  • Restarts the application upon changes
  • Automates the process of restarting the app

Basic Express App Setup

• Import Express:

  const express = require('express');

• Create an Express app instance:

  const app = express();

• Set the port:

  const port = 3001;

• Start the server:

  app.listen(port, () => { console.log(`Running express server on port ${port}`); });

• Running the Application:

  1. Run start script: npm start or npm run start:dev
  2. Verify by visiting: http://localhost:3001

• Issue: "Cannot GET /"

  • Happens because no routes are defined yet

Next Steps

• Focus on GET requests
• Explanation and implementation of GET requests in Express.js

Conclusion

• Next Episode Preview: Setting up a simple GET request
• Closing: Thank you for watching, see you in the next episode. Peace out.