http Module #

In Node.js, the http module is a core module that provides functionality for creating HTTP servers and clients. It is a foundational part of building web applications and APIs. Below is a basic overview of using the http module for server creation in Node.js:

Creating an HTTP Server: #

Use the createServer method to create a basic HTTP server:

const http = require('http');

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

const PORT = 3000;
server.listen(PORT, () => {
    console.log(`Server is running on port ${PORT}`);
});

Handling Requests and Responses: #

The server callback function is executed for every incoming HTTP request. It receives the request (req) and response (res) objects:

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

HTTP Methods and Routing: #

Use the req.method property to determine the HTTP method, enabling basic routing:

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

Handling Query Parameters: #

Use the url module to parse query parameters:

const url = require('url');

const server = http.createServer((req, res) => {
    const parsedUrl = url.parse(req.url, true);
    const name = parsedUrl.query.name || 'Node.js';

    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end(`Hello, ${name}!`);
});

Handling POST Requests: #

For POST requests, use the data event to collect the request body:

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

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

        req.on('end', () => {
            const parsedData = JSON.parse(data);
            res.writeHead(200, { 'Content-Type': 'application/json' });
            res.end(JSON.stringify(parsedData));
        });
    } else {
        res.writeHead(404, { 'Content-Type': 'text/plain' });
        res.end('Not Found');
    }
});

Handling Static Files: #

Serve static files by reading and streaming the file content:

const fs = require('fs');
const path = require('path');

const server = http.createServer((req, res) => {
    const filePath = path.join(__dirname, 'public', req.url);

    fs.readFile(filePath, (err, data) => {
        if (err) {
            res.writeHead(404, { 'Content-Type': 'text/plain' });
            res.end('Not Found');
            return;
        }

        res.writeHead(200, { 'Content-Type': 'text/html' });
        res.end(data);
    });
});

Handling Redirects: #

Redirect requests using the res.writeHead with a 302 status code:

const server = http.createServer((req, res) => {
    if (req.url === '/old') {
        res.writeHead(302, { 'Location': '/new' });
        res.end();
    } else if (req.url === '/new') {
        res.writeHead(200, { 'Content-Type': 'text/plain' });
        res.end('Welcome to the new page!');
    } else {
        res.writeHead(404, { 'Content-Type': 'text/plain' });
        res.end('Not Found');
    }
});

Handling Cookies: #

Parse and set cookies using the req.headers.cookie and res.setHeader:

const server = http.createServer((req, res) => {
    const cookies = req.headers.cookie || '';

    // Set a cookie
    res.setHeader('Set-Cookie', 'username=John; Path=/');

    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end(`Cookies: ${cookies}`);
});

HTTP Server Events: #

Listen for server events such as ‘request’, ‘connection’, and ‘close’:

const server = http.createServer();

server.on('request', (req, res) => {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('Hello, Node.js!');
});

server.on('connection', (socket) => {
    console.log('Client connected');
});

server.on('close', () => {
    console.log('Server closed');
});

server.listen(3000);

HTTPS Server: #

Create an HTTPS server using the https module:

const https = require('https');
const fs = require('fs');

const options = {
    key: fs.readFileSync('private-key.pem'),
    cert: fs.readFileSync('public-cert.pem')
};

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

server.listen(3000);

The http module in Node.js is fundamental for creating web servers, handling requests, and building the backbone of web applications. It provides a versatile set of functionalities, allowing developers to handle different aspects of HTTP communication efficiently. While many modern applications use higher-level frameworks, understanding the basics of the http module is crucial for gaining insights into how web servers operate in a Node.js environment.