Building a Basic HTTP Server with Node.js

1. Introduction

In this tutorial, our goal is to build a basic HTTP server using Node.js. We will be learning the basics of server-side programming, including how to listen and respond to HTTP requests.

What you will learn:
- Basic understanding of server-side programming
- How to create a simple HTTP server with Node.js
- How to listen and respond to HTTP requests

Prerequisites:
- Basic understanding of JavaScript
- Node.js and NPM installed on your machine

2. Step-by-Step Guide

Building an HTTP server with Node.js is quite straightforward. Node.js provides a built-in module called HTTP, which allows Node.js to transfer data over the Hypertext Transfer Protocol (HTTP).

Steps:

1. Create a new Node.js project: Start by initializing a new Node.js project using the command npm init -y in your terminal.
2. Create a new JavaScript file: Let's call it server.js.
3. Import HTTP module: At the top of your server.js file, add the line const http = require('http'); to import the HTTP module.
4. Create server: Now, we will use the http.createServer() method to create an HTTP server.

3. Code Examples

Here's an example of how to create a basic HTTP server that listens on port 3000:

// Importing the HTTP module
const http = require('http');

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

// The server object listens on port 3000
server.listen(3000, '127.0.0.1', () => {
    console.log("Server listening on port 3000");
});

Explanations:
- We are importing the http module provided by Node.js
- The http.createServer() method turns your computer into an HTTP server. It takes a callback function which will be executed each time a client makes a request to your server.
- The callback function takes two arguments: req (the request object) and res (the response object).
- res.statusCode sets the status code to 200, which is HTTP for OK.
- res.setHeader() sets the response header. Here, we are setting the content type to 'text/plain'.
- res.end() ends the response and sends it to the client. Here, we are sending the string 'Hello World\n'.
- Finally, we tell the server to listen on port 3000.

4. Summary

We learned how to create a basic HTTP server using Node.js. We started by initializing a new Node.js project and then created a new JavaScript file. We imported the HTTP module and used the http.createServer() method to create the server.

To continue learning, try adding more features to your server. You could allow it to serve HTML files, add routing, or even build a basic REST API.

Some additional resources include the Node.js docs, Mozilla Developer Network, and various online coding platforms like Codecademy.

5. Practice Exercises

Exercise 1: Modify the server to return a JSON response containing a greeting message.

Exercise 2: Create a server that serves a simple HTML file.

Exercise 3: Add basic routing to your server. For example, requests to '/about' could return a short bio.

Solutions:
1. To return a JSON response, you will need to change the content type to 'application/json' and the response to a JSON string.

res.setHeader('Content-Type', 'application/json');
res.end(JSON.stringify({ message: 'Hello World' }));

1. To serve an HTML file, you will need to use the fs (filesystem) module in Node.js.

const fs = require('fs');

const server = http.createServer((req, res) => {
    res.statusCode = 200;
    res.setHeader('Content-Type', 'text/html');
    fs.readFile('index.html', null, function (error, data) {
        if (error) {
            res.writeHead(404);
            res.write('Whoops! File not found!');
        } else {
            res.write(data);
        }
        res.end();
    });
});

1. To add basic routing, you can use req.url to get the URL of the request.

const server = http.createServer((req, res) => {
    if (req.url === '/about') {
        res.writeHead(200, { 'Content-Type': 'text/plain' });
        res.end('This is the about page.');
    } else {
        res.writeHead(200, { 'Content-Type': 'text/plain' });
        res.end('Hello World');
    }
});

Remember to practice and experiment on your own for better understanding and mastery of the concepts.