node:http

require('http')

The node:http module provides HTTP server and client functionality in Node.js. It’s the foundational module for building web servers and making HTTP requests. This module is built on top of Node.js’s event-driven architecture and uses streams for efficient data handling.

Common Usage

Creating a Simple HTTP Server

const http = require('http');

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

server.listen(3000, () => {
  console.log('Server running on http://localhost:3000');
});

Making HTTP GET Requests

const http = require('http');

const req = http.get('http://example.com', (res) => {
  console.log(`STATUS: ${res.statusCode}`);
  
  res.on('data', (chunk) => {
    console.log(`DATA: ${chunk}`);
  });
  
  res.on('end', () => {
    console.log('Response complete');
  });
});

req.on('error', (err) => {
  console.error(`Error: ${err.message}`);
});

Making HTTP POST Requests

const http = require('http');

const data = JSON.stringify({ name: 'John', age: 30 });

const options = {
  hostname: 'example.com',
  port: 80,
  path: '/api/users',
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'Content-Length': Buffer.byteLength(data)
  }
};

const req = http.request(options, (res) => {
  let body = '';
  
  res.on('data', (chunk) => {
    body += chunk;
  });
  
  res.on('end', () => {
    console.log('Response:', body);
  });
});

req.write(data);
req.end();

Key Classes and Methods

http.createServer()

Creates an HTTP server instance. The request listener receives http.IncomingMessage (req) and http.ServerResponse (res) objects.

const server = http.createServer((req, res) => {
  // Handle request
});

http.request()

Makes an outgoing HTTP request. Returns a http.ClientRequest instance.

const req = http.request(options, (res) => {
  // Handle response
});
req.end();

http.get()

A convenience method for making GET requests. Shorthand for http.request() with method: 'GET'.

http.get('http://example.com', (res) => {
  // Handle response
});

Request and Response Objects

IncomingMessage (req)

The IncomingMessage object represents the HTTP request. It inherits from stream.Readable.

Key Properties:

• req.method — HTTP method (GET, POST, etc.)
• req.url — Request URL
• req.headers — Request headers object
• req.httpVersion — HTTP version

Key Events:

• data — Emitted when a chunk of data is received
• end — Emitted when the entire message is received
• error — Emitted on errors

ServerResponse (res)

The ServerResponse object represents the HTTP response. It inherits from stream.Writable.

Key Methods:

• res.writeHead(statusCode, headers) — Write response headers
• res.write(chunk) — Write response body
• res.end() — Signal response complete
• res.setHeader(name, value) — Set a response header
• res.getHeader(name) — Get a response header
• res.removeHeader(name) — Remove a response header

Examples

Routing Based on URL

const http = require('http');

const server = http.createServer((req, res) => {
  if (req.url === '/') {
    res.writeHead(200, { 'Content-Type': 'text/html' });
    res.end('<h1>Home Page</h1>');
  } else if (req.url === '/about') {
    res.writeHead(200, { 'Content-Type': 'text/html' });
    res.end('<h1>About Page</h1>');
  } else {
    res.writeHead(404, { 'Content-Type': 'text/html' });
    res.end('<h1>404 Not Found</h1>');
  }
});

server.listen(3000);

Handling POST Data

const http = require('http');

const server = http.createServer((req, res) => {
  if (req.method === 'POST') {
    let body = '';
    
    req.on('data', (chunk) => {
      body += chunk.toString();
    });
    
    req.on('end', () => {
      console.log('Received:', body);
      res.writeHead(200, { 'Content-Type': 'application/json' });
      res.end(JSON.stringify({ received: body }));
    });
  } else {
    res.writeHead(405, { 'Content-Type': 'text/plain' });
    res.end('Method not allowed');
  }
});

server.listen(3000);

JSON REST API

const http = require('http');

const users = [
  { id: 1, name: 'Alice' },
  { id: 2, name: 'Bob' }
];

const server = http.createServer((req, res) => {
  // Set CORS headers
  res.setHeader('Access-Control-Allow-Origin', '*');
  res.setHeader('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE');
  res.setHeader('Content-Type', 'application/json');
  
  if (req.url === '/api/users' && req.method === 'GET') {
    res.end(JSON.stringify(users));
  } else {
    res.writeHead(404);
    res.end(JSON.stringify({ error: 'Not found' }));
  }
});

server.listen(3000);

Important Notes

• The http module is a low-level module. For production applications, consider using frameworks like Express.js or Fastify.
• The http module does not support HTTPS. Use the https module for secure connections.
• Always handle errors on both server and client requests to prevent unhandled exceptions.

See Also

• Https::Request — HTTPS server and client
• URL::parse — URL parsing and manipulation