How to handle HTTP requests and responses in Node.js



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In Node.js, handling HTTP requests and responses is a fundamental part of building web applications. You can use the built-in http module or popular third-party libraries like Express.js to simplify the process. Below, I'll provide examples using both the native http module and Express.js.

Using the native http module:

  1. Creating a simple HTTP server:

    javascript
    const http = require('http');

const server = http.createServer((req, res) => {
  // Request handling logic
  res.writeHead(200, { 'Content-Type': 'text/plain' });
  res.end('Hello, World!\n');
});

const PORT = 3000;

server.listen(PORT, () => {
  console.log(`Server running at http://localhost:${PORT}/`);
});

  2. Handling different HTTP methods and routes:

    javascript
    const http = require('http');

const server = http.createServer((req, res) => {
  // Routing
  if (req.method === 'GET' && req.url === '/') {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('Hello, World!\n');
  } else if (req.method === 'GET' && req.url === '/about') {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('About us\n');
  } else {
    res.writeHead(404, { 'Content-Type': 'text/plain' });
    res.end('Not Found\n');
  }
});

const PORT = 3000;

server.listen(PORT, () => {
  console.log(`Server running at http://localhost:${PORT}/`);
});

Using Express.js:

  1. Installing Express:

    bash
    npm install express

  2. Creating a simple Express server:

    javascript
    const express = require('express');
const app = express();
const PORT = 3000;

app.get('/', (req, res) => {
  res.send('Hello, World!');
});

app.listen(PORT, () => {
  console.log(`Server running at http://localhost:${PORT}/`);
});

  3. Handling different routes and HTTP methods with Express:

    javascript
    const express = require('express');
const app = express();
const PORT = 3000;

app.get('/', (req, res) => {
  res.send('Hello, World!');
});

app.get('/about', (req, res) => {
  res.send('About us');
});

// Handling 404 Not Found
app.use((req, res) => {
  res.status(404).send('Not Found');
});

app.listen(PORT, () => {
  console.log(`Server running at http://localhost:${PORT}/`);
});

Both approaches are valid, and the choice between them depends on your project's complexity and requirements. Express.js is a popular choice for its simplicity and powerful features for building web applications.

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