Node.js HTTP Module

The Node.js http module allows you to create web servers and handle HTTP requests and responses. This guide covers key concepts, examples, and best practices for using the http module effectively.

Key Concepts of the HTTP Module

• HTTP Server: A server that listens for HTTP requests and responds to them.
• Request and Response Objects: Objects representing the HTTP request and response, respectively.
• Routing: Handling different paths and methods (GET, POST, etc.) within the server.

Creating an HTTP Server

Use the http.createServer method to create an HTTP server that listens for requests and sends responses:

Example: Basic HTTP Server

// http-server.js
const http = require('http');

const hostname = '127.0.0.1';
const port = 3000;

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

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

Handling Different Routes

Use the request object to handle different routes and methods:

Example: Handling Routes

// http-routes.js
const http = require('http');

const hostname = '127.0.0.1';
const port = 3000;

const server = http.createServer((req, res) => {
    res.setHeader('Content-Type', 'text/plain');

    if (req.method === 'GET' && req.url === '/') {
        res.statusCode = 200;
        res.end('Hello, World!\n');
    } else if (req.method === 'GET' && req.url === '/about') {
        res.statusCode = 200;
        res.end('About Page\n');
    } else {
        res.statusCode = 404;
        res.end('Not Found\n');
    }
});

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

Handling POST Requests

Use the request object to handle POST requests and parse incoming data:

Example: Handling POST Requests

// http-post.js
const http = require('http');

const hostname = '127.0.0.1';
const port = 3000;

const server = http.createServer((req, res) => {
    if (req.method === 'POST' && req.url === '/data') {
        let body = '';

        req.on('data', chunk => {
            body += chunk.toString();
        });

        req.on('end', () => {
            res.statusCode = 200;
            res.setHeader('Content-Type', 'text/plain');
            res.end(`Data received: ${body}\n`);
        });
    } else {
        res.statusCode = 404;
        res.end('Not Found\n');
    }
});

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

Serving Static Files

Use the fs module to read and serve static files:

Example: Serving Static Files

// http-static.js
const http = require('http');
const fs = require('fs');
const path = require('path');

const hostname = '127.0.0.1';
const port = 3000;

const server = http.createServer((req, res) => {
    if (req.method === 'GET' && req.url === '/') {
        fs.readFile(path.join(__dirname, 'index.html'), (err, data) => {
            if (err) {
                res.statusCode = 500;
                res.setHeader('Content-Type', 'text/plain');
                res.end('Internal Server Error\n');
                return;
            }
            res.statusCode = 200;
            res.setHeader('Content-Type', 'text/html');
            res.end(data);
        });
    } else {
        res.statusCode = 404;
        res.end('Not Found\n');
    }
});

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

Best Practices for Using the HTTP Module

• Use Asynchronous Methods: Prefer asynchronous methods to avoid blocking the event loop.
• Error Handling: Implement robust error handling to manage runtime exceptions and send appropriate responses.
• Security: Validate and sanitize inputs to prevent security vulnerabilities such as SQL injection and XSS.
• Logging: Implement logging to monitor HTTP requests and responses for debugging and analysis.
• Modular Code: Organize your code into reusable modules to improve maintainability.

Testing HTTP Servers

Test your HTTP servers using frameworks like Mocha and Chai:

Example: Testing HTTP Servers with Mocha and Chai

// Install Mocha, Chai, and Supertest
// npm install --save-dev mocha chai supertest

// test/http-server.test.js
const chai = require('chai');
const expect = chai.expect;
const request = require('supertest');
const http = require('http');

describe('HTTP Server', () => {
    let server;

    before((done) => {
        server = http.createServer((req, res) => {
            res.statusCode = 200;
            res.setHeader('Content-Type', 'text/plain');
            res.end('Hello, World!\n');
        }).listen(3000, done);
    });

    after((done) => {
        server.close(done);
    });

    it('should respond with "Hello, World!"', (done) => {
        request(server)
            .get('/')
            .expect('Content-Type', /text\/plain/)
            .expect(200, 'Hello, World!\n', done);
    });
});

// Run tests with Mocha
// npx mocha test/http-server.test.js

Key Points

Conclusion

The Node.js http module allows you to create web servers and handle HTTP requests and responses. By understanding and implementing the key concepts, examples, and best practices covered in this guide, you can effectively use the http module in your Node.js applications. Happy coding!