Node.js HTTP Module

Last modified on: October 19, 2024

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<h3>Node.js HTTP Module: A Comprehensive Guide</h3>
<p>The <strong>HTTP module</strong> in Node.js is a built-in module that allows you to create HTTP servers and clients. It provides a powerful set of tools for handling HTTP requests and responses, making it essential for building web applications and APIs. This guide will cover the basics of the HTTP module, how to create a simple HTTP server, handle routing, and work with HTTP requests and responses.</p>
<hr />
<h3>What is the HTTP Module?</h3>
<p>The HTTP module is part of Node.js's core modules and provides functionality for both creating servers and sending requests to external resources. It abstracts the complexities of HTTP protocol, enabling developers to handle HTTP requests and responses easily.</p>
<h4>Key Features of the HTTP Module:</h4>
<ul>
<li><strong>Create HTTP Servers</strong>: Allows you to create web servers that can listen for requests and respond accordingly.</li>
<li><strong>Handle Requests and Responses</strong>: Provides methods to work with incoming requests and outgoing responses.</li>
<li><strong>Support for HTTP/HTTPS</strong>: Can be used for both HTTP and HTTPS servers.</li>
<li><strong>Stream Interface</strong>: Uses streams to handle data efficiently, enabling non-blocking I/O operations.</li>
</ul>
<hr />
<h3>Setting Up an HTTP Server</h3>
<p>Let's start by creating a simple HTTP server using the HTTP module.</p>
<h4>Step 1: Create a New Project</h4>
<ol>
<li>
<p>Create a new directory for your project:</p>
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<pre class="language-javascript"><code>mkdir http-server-example
cd http-server-example</code></pre>
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</li>
<li>
<p>Initialize a new Node.js project:</p>
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<pre class="language-javascript"><code>npm init -y</code></pre>
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</li>
</ol>
<h4>Step 2: Create the Server</h4>
<ol>
<li>Create a file named <code>server.js</code> and open it in your favorite text editor.</li>
<li>Add the following code to create a basic HTTP server:</li>
</ol>
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<pre class="language-javascript"><code>// Load the HTTP module
const http = require('http');

// Create the server
const server = http.createServer((req, res) =&gt; {
    // Set the response HTTP header with HTTP status and content type
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    
    // Send the response body
    res.end('Hello, World from the HTTP module!\n');
});

// Server listens on port 3000
server.listen(3000, () =&gt; {
    console.log('Server running at http://localhost:3000/');
});</code></pre>
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<h4>Step 3: Run the Server</h4>
<p>In your terminal, run the server with the following command:</p>
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<pre class="language-javascript"><code>node server.js</code></pre>
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<p>You should see the output:</p>
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<pre class="language-javascript"><code>Server running at http://localhost:3000/</code></pre>
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<h4>Step 4: Test the Server</h4>
<p>Open your web browser and navigate to <code>http://localhost:3000/</code>. You should see the message:</p>
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<pre class="language-javascript"><code>Hello, World from the HTTP module!</code></pre>
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<hr />
<h3>Handling HTTP Requests</h3>
<p>You can handle different HTTP requests (GET, POST, etc.) and route them accordingly.</p>
<h4>Example: Handling GET and POST Requests</h4>
<p>Modify your <code>server.js</code> file to handle both GET and POST requests:</p>
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<pre class="language-javascript"><code>const http = require('http');

// Create the server
const server = http.createServer((req, res) =&gt; {
    // Handle GET requests
    if (req.method === 'GET') {
        res.writeHead(200, { 'Content-Type': 'text/plain' });
        res.end('This is a GET request.\n');
    }
    // Handle POST requests
    else if (req.method === 'POST') {
        res.writeHead(200, { 'Content-Type': 'text/plain' });
        res.end('This is a POST request.\n');
    } else {
        // Handle other request types
        res.writeHead(405, { 'Content-Type': 'text/plain' });
        res.end('Method Not Allowed\n');
    }
});

// Server listens on port 3000
server.listen(3000, () =&gt; {
    console.log('Server running at http://localhost:3000/');
});</code></pre>
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<h4>Step 5: Test GET and POST Requests</h4>
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<li>
<p>Open your browser and navigate to <code>http://localhost:3000/</code> to test the GET request. You should see the message:</p>
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<pre class="language-javascript"><code>This is a GET request.</code></pre>
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</li>
<li>
<p>To test the POST request, you can use a tool like <strong>Postman</strong> or <strong>curl</strong>. For example, using <code>curl</code> in the terminal:</p>
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<pre class="language-javascript"><code>curl -X POST http://localhost:3000/</code></pre>
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</li>
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<p>You should see the message:</p>
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<pre class="language-javascript"><code>This is a POST request.</code></pre>
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<hr />
<h3>Routing Requests</h3>
<p>For a more structured approach, you can implement basic routing based on the URL of incoming requests.</p>
<h4>Example: Basic Routing</h4>
<p>Modify your server to handle different routes:</p>
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<pre class="language-javascript"><code>const http = require('http');

// Create the server
const server = http.createServer((req, res) =&gt; {
    // Handle routing based on the URL
    if (req.method === 'GET') {
        if (req.url === '/') {
            res.writeHead(200, { 'Content-Type': 'text/plain' });
            res.end('Welcome to the homepage!\n');
        } else if (req.url === '/about') {
            res.writeHead(200, { 'Content-Type': 'text/plain' });
            res.end('This is the about page.\n');
        } else {
            res.writeHead(404, { 'Content-Type': 'text/plain' });
            res.end('Page not found.\n');
        }
    } else {
        // Handle other request types
        res.writeHead(405, { 'Content-Type': 'text/plain' });
        res.end('Method Not Allowed\n');
    }
});

// Server listens on port 3000
server.listen(3000, () =&gt; {
    console.log('Server running at http://localhost:3000/');
});</code></pre>
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<h4>Step 6: Test the Routes</h4>
<ol>
<li>
<p>Navigate to <code>http://localhost:3000/</code> to see the homepage message:</p>
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<pre class="language-javascript"><code>Welcome to the homepage!</code></pre>
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</li>
<li>
<p>Navigate to <code>http://localhost:3000/about</code> to see the about page message:</p>
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<pre class="language-javascript"><code>This is the about page.</code></pre>
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</li>
<li>
<p>Navigate to a non-existent page, like <code>http://localhost:3000/contact</code>, to see the 404 error message:</p>
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<pre class="language-javascript"><code>Page not found.</code></pre>
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</li>
</ol>
<hr />
<h3>Handling Query Parameters</h3>
<p>You can also handle query parameters in the URL. To parse the URL and extract query parameters, you can use the <code>url</code> module.</p>
<h4>Example: Handling Query Parameters</h4>
<p>Modify your server to read query parameters:</p>
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<pre class="language-javascript"><code>const http = require('http');
const url = require('url');

// Create the server
const server = http.createServer((req, res) =&gt; {
    // Parse the URL
    const parsedUrl = url.parse(req.url, true);
    
    // Handle routing
    if (req.method === 'GET') {
        if (parsedUrl.pathname === '/greet') {
            const name = parsedUrl.query.name || 'World';
            res.writeHead(200, { 'Content-Type': 'text/plain' });
            res.end(`Hello, ${name}!\n`);
        } else {
            res.writeHead(404, { 'Content-Type': 'text/plain' });
            res.end('Page not found.\n');
        }
    } else {
        res.writeHead(405, { 'Content-Type': 'text/plain' });
        res.end('Method Not Allowed\n');
    }
});

// Server listens on port 3000
server.listen(3000, () =&gt; {
    console.log('Server running at http://localhost:3000/');
});</code></pre>
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<h4>Step 7: Test Query Parameters</h4>
<ol>
<li>
<p>Navigate to <code>http://localhost:3000/greet?name=Alice</code> to see the greeting message:</p>
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<pre class="language-javascript"><code>Hello, Alice!</code></pre>
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</li>
<li>
<p>Navigate to <code>http://localhost:3000/greet</code> to see the default greeting:</p>
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<pre class="language-javascript"><code>Hello, World!</code></pre>
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</li>
</ol>
<hr />
<h3>Conclusion</h3>
<p>The HTTP module in Node.js is a powerful tool for creating web servers and handling HTTP requests. By learning how to use this module effectively, you can build robust web applications and APIs.</p>
<p>In this guide, we covered:</p>
<ul>
<li>Setting up a basic HTTP server.</li>
<li>Handling different types of requests (GET and POST).</li>
<li>Implementing basic routing.</li>
<li>Handling query parameters.</li>
</ul>
<p>With these foundations, you can further explore more advanced features of the HTTP module, integrate middleware using frameworks like Express, and build complex applications.</p>
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