Express.js Crash Course

Express.js is a minimal and flexible web application framework for Node.js. It simplifies building APIs and web apps by providing a robust set of features with minimal overhead.

Why use Express?

• Fast setup for REST APIs.
• Works seamlessly with middleware.
• Great for single-page apps (SPAs), mobile backends, and microservices.

Getting started:

1. Install Express: bashКопироватьРедактироватьnpm install express
2. Create a basic server: jsКопироватьРедактироватьconst express = require('express'); const app = express(); app.get('/', (req, res) => { res.send('Hello World!'); }); app.listen(3000, () => { console.log('Server running on port 3000'); });

Core concepts:

• Routing: Handle GET, POST, PUT, DELETE requests.
• Middleware: Functions that modify requests/responses (e.g., authentication, logging).
• Static files: Serve HTML, CSS, and JS from a public folder.

Popular middleware:

• body-parser for JSON parsing.
• cors for cross-origin resource sharing.
• morgan for logging.

Express is simple yet powerful—ideal for both beginners and professionals building scalable APIs or full-stack apps (especially with MongoDB and React or Angular).