NODEJS

🔹 What is Node.js?

Node.js is an open-source, cross-platform runtime environment that allows you to run JavaScript outside the browser, mainly on the server side.

It is built on the V8 engine, which is also used in the Google Chrome browser.

🔹 Why Node.js is Important

Before Node.js, JavaScript was only used in browsers (frontend).
👉 Node.js allows JavaScript to be used for:

Backend development
Server-side scripting
Building APIs

🔹 Key Features of Node.js

✔ 1. Asynchronous (Non-blocking)

Handles multiple tasks at the same time
Does not wait for one task to finish

✔ 2. Fast Performance

Uses V8 engine for high-speed execution

✔ 3. Event-Driven Architecture

Executes code based on events (like user actions, requests)

✔ 4. Single Threaded but Scalable

Uses one main thread but handles many connections efficiently

✔ 5. Cross-Platform

Works on Windows, Linux, macOS

🔹 How Node.js Works

Node.js uses an event loop:

Receives request
Processes it asynchronously
Sends response

👉 This makes it very fast and efficient.

🔹 Basic Example of Node.js

const http = require(‘http’);

const server = http.createServer((req, res) => {
res.write(“Hello from Node.js”);
res.end();
});

server.listen(3000);

👉 This creates a simple web server.

🔹 Core Modules in Node.js

Node.js has built-in modules like:

http → Create server
fs → File system
path → Handle file paths
os → System information

🔹 NPM (Node Package Manager)

npm is used to install libraries (packages).

Example:

npm install express

🔹 Popular Frameworks with Node.js

Express.js → Web framework
NestJS → Backend framework
Socket.io → Real-time apps

🔹 Applications of Node.js

Web servers
REST APIs
Real-time apps (chat apps)
Streaming services
Online games

🔹 Advantages

✔ Fast and efficient
✔ Uses JavaScript (same language for frontend & backend)
✔ Large ecosystem (npm)
✔ Great for real-time applications

🔹 Limitations

✖ Not ideal for CPU-heavy tasks
✖ Callback complexity (can be confusing)

🔹 Node.js vs Other Technologies

Faster than traditional servers in many cases
Easier if you already know JavaScript
Less suitable for heavy computation than languages like C++

🔹 Conclusion

Node.js is a powerful backend technology that allows developers to build fast, scalable, and real-time applications using JavaScript. It has become one of the most popular tools in modern web development.