Simple HTTP Server in Node.js

📌 INTRODUCTION

Node.js allows developers to create web servers very easily using its built-in http module. This module helps us handle client requests and send responses from the server.

A simple HTTP server is one of the first and most important programs in Node.js because it introduces:

• Server creation
• Request handling
• Response sending
• Port listening

In this program, we will create a basic HTTP server using Node.js that listens for requests and responds with simple text or HTML.

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📘 PROBLEM STATEMENT

👉 Develop a simple HTTP server in Node.js using the built-in http module. The server should listen for incoming requests and respond with basic text or HTML.

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💡 CONCEPTS USED

• Node.js http module
• Server creation
• Request and response objects
• Port listening
• Basic backend programming

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🧠 LOGIC EXPLANATION

The server works in the following way:

1. Import the http module
2. Create a server using http.createServer()
3. Accept client request using req
4. Send response using res
5. Listen on a port using server.listen()

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💻 PROGRAM CODE

Create a file named server.js and write the following code:

const http = require("http");

const server = http.createServer((req, res) => {
  res.writeHead(200, { "Content-Type": "text/plain" });
  res.end("Hello, World! This is a simple HTTP server in Node.js.");
});

server.listen(3000, () => {
  console.log("Server is running at http://localhost:3000");
});

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▶️ HOW TO RUN THE PROGRAM

Open terminal in your project folder and run:

node server.js

Now open browser and visit:

http://localhost:3000

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🖥️ OUTPUT

Terminal Output

Server is running at http://localhost:3000

Browser Output

Hello, World! This is a simple HTTP server in Node.js.

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🔍 STEP-BY-STEP EXPLANATION

1. Import the http Module

const http = require("http");

This loads the built-in HTTP module of Node.js.

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2. Create the Server

const server = http.createServer((req, res) => {

• req represents the incoming request
• res represents the response sent back to the client

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3. Set Response Header

res.writeHead(200, { "Content-Type": "text/plain" });

• 200 means request was successful
• text/plain means plain text response will be sent

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4. Send the Response

res.end("Hello, World! This is a simple HTTP server in Node.js.");

This sends the final response to the browser.

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5. Start Listening on a Port

server.listen(3000, () => {

This tells the server to run on port 3000.

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🎯 IMPORTANT METHODS USED

Method	Purpose
http.createServer()	Creates an HTTP server
res.writeHead()	Sets response status and headers
res.end()	Ends the response and sends data
server.listen()	Starts the server on a port

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⚡ VERSION 2: RETURN HTML RESPONSE

You can also return HTML instead of plain text.

const http = require("http");

const server = http.createServer((req, res) => {
  res.writeHead(200, { "Content-Type": "text/html" });
  res.end("<h1>Welcome to Node.js Server</h1><p>This is an HTML response.</p>");
});

server.listen(3000, () => {
  console.log("Server is running at http://localhost:3000");
});

Browser Output

Welcome to Node.js Server
This is an HTML response.

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⚡ VERSION 3: HANDLE DIFFERENT ROUTES

We can show different output for different URLs.

const http = require("http");

const server = http.createServer((req, res) => {
  if (req.url === "/") {
    res.writeHead(200, { "Content-Type": "text/html" });
    res.end("<h1>Home Page</h1>");
  } else if (req.url === "/about") {
    res.writeHead(200, { "Content-Type": "text/html" });
    res.end("<h1>About Page</h1>");
  } else {
    res.writeHead(404, { "Content-Type": "text/plain" });
    res.end("Page Not Found");
  }
});

server.listen(3000, () => {
  console.log("Server is running at http://localhost:3000");
});

Example URLs

• http://localhost:3000/ → Home Page
• http://localhost:3000/about → About Page
• any other URL → Page Not Found

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⚡ VERSION 4: SEND JSON RESPONSE

A server can also send JSON data.

const http = require("http");

const server = http.createServer((req, res) => {
  const user = {
    name: "Nyra",
    course: "BBA"
  };

  res.writeHead(200, { "Content-Type": "application/json" });
  res.end(JSON.stringify(user));
});

server.listen(3000, () => {
  console.log("Server running on http://localhost:3000");
});

Browser Output

{"name":"Kavita","course":"MCA"}

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🌟 WHY THIS PROGRAM IS IMPORTANT

This program is important because it teaches the basics of backend development:

• How a server works
• How browser requests are handled
• How responses are sent
• How different data formats can be returned

It is the foundation for:

• Express.js applications
• REST APIs
• Full stack web development

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📚 REAL-WORLD USE CASE

Simple HTTP servers are used in:

• Testing backend logic
• Serving HTML pages
• Sending JSON APIs
• Learning server-side development
• Building web applications

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❓ VIVA QUESTIONS (IMPORTANT)

Q1. What is the http module in Node.js?

👉 It is a built-in module used to create web servers and handle HTTP requests and responses.

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Q2. What does http.createServer() do?

👉 It creates a new HTTP server.

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Q3. What are req and res?

👉 req is the request object and res is the response object.

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Q4. What is the use of res.writeHead()?

👉 It sets the response status code and headers.

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Q5. What does res.end() do?

👉 It sends the response to the client and ends the request-response cycle.

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Q6. What is the purpose of server.listen()?

👉 It starts the server on a specific port.

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Q7. What is the difference between text/plain and text/html?

👉 text/plain sends plain text, while text/html sends HTML content.

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Q8. Can Node.js return JSON data?

👉 Yes, by using application/json as content type and JSON.stringify().

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🔗 RELATED POSTS

👉 MCA 168 Full Stack Development Lab Programs List
👉 Node.js File Upload Application – Program 21
👉 Node.js File Operations – Program 20

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📌 CONCLUSION

A simple HTTP server in Node.js is the first step toward backend development. It helps you understand how servers handle requests and send responses.

👉 Practice the plain text version first, then try HTML, routes, and JSON responses. This will make your understanding much stronger.

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