ExpressJS Crash Course

Introduction

• Updated version of the previous course
• Node.js Crash Course Link provided
• Node.js is a JavaScript runtime
• Suggested to watch the Node.js crash course first for a better understanding

Course Outline

• What is Express.js and its uses
• Projects: Creating Routes, Request Response Objects, Middleware, Error Handling, and more
• Mal Utilized by large companies (IBM, Uber, Nike) and start-ups

What is Express.js

• Minimal Node.js web framework with versatile features for web/mobile apps
• Used for server-side applications and APIs/microservices
• Commonly used for backend APIs consumed by frontend frameworks (MERN, MEAN, MEVN, etc.)
• Flexible and Unopinionated framework: Few rules, more customizability
• Popular for smaller projects and start-ups
• Simplifies HTTP request handling

Types of Web Frameworks

• Opinionated Frameworks:
  • Structured with guided rules/conventions
  • Includes many features out-of-the-box
  • Examples: Ruby on Rails, Django, Laravel, NestJS (Node.js)
• Unopinionated Frameworks:
  • Flexible with minimal rules
  • Fewer features out-of-the-box, but highly customizable
  • Examples: Express.js

Prerequisites for Learning ExpressJS

• Strong understanding of JavaScript (including ES6 features like arrow functions, destructuring, async/await)
• Basic Node.js knowledge (recommended 2-hour crash course)
• Familiarity with npm and handling JSON data

Course Practical Sections

1. Server Setup: Creating a package.json and installing Express
2. Setting Up Basic Server with routes
   • Using app.listen, app.get for starting the server and handling requests
   • Using Nodemon or --watch flag for auto-restart
3. Serving Static HTML Files
   • Using middleware app.use(express.static())
4. Handling JSON APIs
   • Setting up API routes to send JSON data
   • Using Postman for testing different HTTP methods
5. Working with Environment Variables
   • Creating and using a .env file without a third-party package
6. Handling Dynamic Routes and Params
   • Using req.params and req.query to handle route and query parameters
7. Managing HTTP Status Codes
   • Properly sending statuses like 200, 404, 500 for different scenarios
8. Optimizing Route File Structure
   • Moving route definitions to separate files and using Express Router
9. Handling Request Body Data
   • Parsing JSON and form-data using body-parser middleware adapted within Express
10. CRUD Operations
    • Implementing CRUD endpoints for posts
    • Using basic error handling and custom messages

Middleware in Express

• Definition and Examples
  • Creating a logger middleware and using it at route and application levels
  • Importing third-party libraries (colors to add color to console logs)

Custom Error Handling

• Using custom middleware for error handling
• Handling different types of errors (404, 500, etc.) using the error object in middleware

Controllers

• Moving logic to controllers for cleaner code
• Importing and using controller functions in route files

Frontend Interaction Example

• Setting up a Static Folder and Loading HTML Files
  • Using vanilla JavaScript to interact with Express API
  • Creating forms and using the Fetch API to send/receive data

Template Engines (Quick Overview)

• Using ejs Template Engine
  • Setting up ejs in Express and rendering dynamic HTML
  • Passing variables and arrays from routes to views
  • Using partials and layouts for repeated sections (like headers)

Conclusion

• Encouragement to keep practicing and understanding will solidify over time.

Additional Resources

• Express Documentation: Express - Node.js web application framework