Node.js HTTP Module

The http module in Node.js provides the necessary functionality to create web servers and handle HTTP requests and responses. It is built into Node.js and can be used to build web applications, APIs, or simply handle incoming HTTP requests.

 

Key Features of the HTTP Module

1. Creating HTTP Servers: You can create a simple server to handle HTTP requests and send responses.
2. Handling Requests: The module allows you to parse incoming HTTP requests and process data.
3. Sending Responses: It enables sending various types of HTTP responses, including status codes, headers, and content.
4. Customizable Server Configuration: You can configure the server to handle different request methods, headers, and data types.

 

Creating an HTTP Server

1. http.createServer()

The http.createServer() method is used to create an HTTP server that listens for incoming requests and sends responses.

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 port 3000');
});

Output:

Server running on port 3000

• When a user accesses the server on port 3000, they will see the response "Hello, World!" in their browser.

 

Handling Different Request Methods

The HTTP server can handle different types of HTTP methods, such as GET, POST, and PUT. The request object provides access to the request method and headers.

1. Handling GET Requests

const http = require('http');

const server = http.createServer((req, res) => {
  if (req.method === 'GET') {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('This is a GET request');
  }
});

server.listen(3000, () => {
  console.log('Server running on port 3000');
});

Output:

This is a GET request

• When a GET request is made to the server, the response will contain "This is a GET request."

2. Handling POST Requests

const http = require('http');

const server = http.createServer((req, res) => {
  if (req.method === 'POST') {
    let body = '';
    req.on('data', chunk => {
      body += chunk;
    });

    req.on('end', () => {
      res.writeHead(200, { 'Content-Type': 'text/plain' });
      res.end(`Received POST data: ${body}`);
    });
  }
});

server.listen(3000, () => {
  console.log('Server running on port 3000');
});

Output:

Received POST data: {"name":"John","age":30}

• When a POST request is made, the server processes the incoming data and responds with it.

 

Sending HTTP Responses

You can send various types of HTTP responses, including status codes and headers, using the res.writeHead() method.

1. Sending a 404 Error

const http = require('http');

const server = http.createServer((req, res) => {
  res.writeHead(404, { 'Content-Type': 'text/plain' });
  res.end('Page Not Found');
});

server.listen(3000, () => {
  console.log('Server running on port 3000');
});

Output:

Page Not Found

• This sends a 404 status code with the message "Page Not Found."

 

Making HTTP Requests

Node.js also allows you to make HTTP requests using the http module.

1. Making a GET Request

const http = require('http');

http.get('http://www.example.com', (res) => {
  let data = '';
  res.on('data', (chunk) => {
    data += chunk;
  });

  res.on('end', () => {
    console.log(data);
  });
});

• This makes a GET request to http://www.example.com and logs the response data.

 

Summary

The http module in Node.js is essential for creating web servers and handling HTTP requests and responses. With it, you can create a server, process different request types (such as GET and POST), send responses with custom status codes and headers, and even make HTTP requests to external servers. This module forms the backbone of building APIs, web applications, and services in Node.js.