Creating a Basic HTTP Server in Node.js

One of the key features of Node.js is its ability to handle HTTP requests and responses, making it an excellent choice for building web servers. In this article, we will explore how to create a basic HTTP server in Node.js, understand its components, and get started with handling HTTP requests and responses.

What is an HTTP Server?

An HTTP server listens for incoming HTTP requests from clients (usually web browsers or other applications) and responds with appropriate data, such as HTML, JSON, or file contents. The server communicates over the HyperText Transfer Protocol (HTTP) and is the backbone of web applications.

In Node.js, you can create an HTTP server using the built-in http module, which provides an easy-to-use API for handling HTTP requests and responses.

Setting Up Your Node.js Environment

Before you begin, ensure that you have Node.js installed. If you haven’t installed Node.js yet, you can download it from nodejs.org.

To check if Node.js is installed, open your terminal and type:

node -v

You should see the version number of Node.js printed out. If it’s not installed, you can follow the instructions on the Node.js website to install it.

Creating a Basic HTTP Server

Let’s walk through creating a simple HTTP server that listens on a specified port and responds with a “Hello, World!” message when accessed.

1. Create a New Project Folder: Start by creating a new folder for your project:

   mkdir my-http-server
   cd my-http-server
   

2. Create the Server File: Create a new file called server.js in your project folder:

   touch server.js
   

3. Write the HTTP Server Code: Open the server.js file and add the following code:

   const http = require('http');
   
   // Create an HTTP server
   const server = http.createServer((req, res) => {
       // Set the response HTTP status code and content type
       res.statusCode = 200;  // Status Code 200 means OK
       res.setHeader('Content-Type', 'text/plain');
   
       // Send the response body
       res.end('Hello, World!');
   });
   
   // The server will listen on port 3000
   server.listen(3000, '127.0.0.1', () => {
       console.log('Server running at http://127.0.0.1:3000/');
   });
   

   Explanation:

   • http.createServer() creates the server. It takes a callback function with two arguments: req (request) and res (response).
   • res.statusCode = 200; sets the HTTP status code to 200, which indicates that the request was successful.
   • res.setHeader('Content-Type', 'text/plain'); sets the content type of the response to plain text.
   • res.end('Hello, World!'); sends the response body, which in this case is the string “Hello, World!”.
   • server.listen(3000, '127.0.0.1', ...) tells the server to listen for requests on IP address 127.0.0.1 (localhost) and port 3000.
4. Start the Server: In your terminal, run the following command to start the server:

   node server.js
   

   You should see the output:

   Server running at http://127.0.0.1:3000/
   

5. Test the Server: Open your web browser and go to http://127.0.0.1:3000/. You should see the message “Hello, World!” displayed in the browser.

Handling Different HTTP Requests

The basic HTTP server we just created responds with the same message for every request. To make it more useful, we can handle different types of HTTP requests (GET, POST, etc.) and different routes.

1. Handling Different HTTP Methods: You can check the req.method to handle different HTTP methods like GET, POST, PUT, and DELETE. Here’s an example where we handle GET and POST requests:

   const http = require('http');
   
   const server = http.createServer((req, res) => {
       // Handle GET request
       if (req.method === 'GET') {
           res.statusCode = 200;
           res.setHeader('Content-Type', 'text/plain');
           res.end('GET request received!');
       }
       // Handle POST request
       else if (req.method === 'POST') {
           res.statusCode = 200;
           res.setHeader('Content-Type', 'text/plain');
           res.end('POST request received!');
       } else {
           res.statusCode = 405;  // Method Not Allowed
           res.setHeader('Content-Type', 'text/plain');
           res.end('Method Not Allowed');
       }
   });
   
   server.listen(3000, '127.0.0.1', () => {
       console.log('Server running at http://127.0.0.1:3000/');
   });
   

2. Handling Routes: You can also handle different routes by checking req.url:

   const http = require('http');
   
   const server = http.createServer((req, res) => {
       if (req.method === 'GET' && req.url === '/') {
           res.statusCode = 200;
           res.setHeader('Content-Type', 'text/plain');
           res.end('Welcome to the Home Page!');
       } else if (req.method === 'GET' && req.url === '/about') {
           res.statusCode = 200;
           res.setHeader('Content-Type', 'text/plain');
           res.end('This is the About Page.');
       } else {
           res.statusCode = 404;
           res.setHeader('Content-Type', 'text/plain');
           res.end('Page Not Found');
       }
   });
   
   server.listen(3000, '127.0.0.1', () => {
       console.log('Server running at http://127.0.0.1:3000/');
   });
   

   In this example, the server responds with different messages depending on the URL path (/ for the home page and /about for the about page). If an unknown path is requested, it returns a 404 error message.

Conclusion

In this article, we’ve created a basic HTTP server using Node.js’s built-in http module. This server listens for HTTP requests, handles different HTTP methods (GET, POST), and responds with different messages depending on the request URL. This simple server is a foundation for building more complex applications such as REST APIs, dynamic web servers, or even web apps.

By understanding how to create and manage HTTP servers, you can start building your own web applications and services with Node.js.