HTTP Module

Before using frameworks like Express, it's important to understand how Node.js handles web requests using its built-in http module.

1. Creating a Basic Server

The createServer method takes a callback function that runs every time a request hits your server.

const http = require('http');

const server = http.createServer((req, res) => {
  // req = Request (what comes in)
  // res = Response (what goes out)
  
  res.statusCode = 200;
  res.setHeader('Content-Type', 'text/plain');
  res.end('Hello from the Server!');
});

const PORT = 5000;
server.listen(PORT, () => {
  console.log(`Server running at http://localhost:${PORT}/`);
});

2. Handling Routes

With the native HTTP module, you have to manually check the req.url.

const http = require('http');

const server = http.createServer((req, res) => {
  if (req.url === '/') {
    res.write('<h1>Welcome to Home Page</h1>');
    res.end();
  } else if (req.url === '/about') {
    res.end('<h1>About Us</h1>');
  } else {
    res.statusCode = 404;
    res.end('<h1>Page Not Found</h1>');
  }
});

server.listen(5000);

3. Responding with JSON

For APIs, you'll often need to send JSON data instead of HTML.

const server = http.createServer((req, res) => {
  const users = [
    { id: 1, name: 'John Doe' },
    { id: 2, name: 'Jane Smith' }
  ];

  res.writeHead(200, { 'Content-Type': 'application/json' });
  res.end(JSON.stringify(users));
});