node4.xt

Chapter 4 – HTTP Module & Creating a Basic Server
1. What is the HTTP Module?

Node.js has a built-in module named http that allows you to:

Create a server

Handle requests & responses

Send data to the browser

Build APIs

No installation needed:

const http = require("http");

2. Creating a Simple Server

A server listens for requests and sends back responses.

Basic structure:

http.createServer((req, res) => {
    res.write("Hello from Node.js Server");
    res.end();
}).listen(3000);


req → request from the client

res → reply from server

.listen(3000) → server starts at port 3000

3. Request & Response Explanation
Request (req)

Contains:

URL (/home, /about)

HTTP Method (GET, POST)

Headers

Response (res)

Used to send:

text

HTML

JSON

status codes

Example:

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

4. Serving HTML Content

You can send HTML directly:

res.write("<h1>Welcome</h1>");


Or you can read HTML files and send them using fs module.

5. Routing in Node.js (Without Express)

You can manually create routes:

if (req.url === "/") {
    res.end("Home Page");
}
else if (req.url === "/about") {
    res.end("About Page");
}
else {
    res.end("404 Page Not Found");
}

6. Sending JSON Response
const data = { name: "Mounika", language: "Node.js" };
res.end(JSON.stringify(data));

7. Summary of This Chapter

By completing Chapter 4, you understand:

What HTTP module is

How to create a Node.js server

Handling requests and responses

Sending HTML and JSON

Basic routing without Express

This is the foundation for building backend systems and APIs.