Node.js Introduction

What is Node.js?

Node.js is an open-source, cross-platform JavaScript runtime environment that allows you to run JavaScript outside the browser.
It uses the powerful Google V8 engine, which makes it fast and efficient.

With Node.js, you can build:

Web servers
APIs
Real-time applications (chat apps, live updates)
Command-line tools
Streaming applications
IoT systems

Why Node.js? (Key Features)

1. Asynchronous & Non-Blocking

Node.js uses an event-driven, non-blocking I/O model, meaning it can handle thousands of requests simultaneously without waiting.

2. Single-Threaded but Highly Scalable

One thread handles all requests using the event loop, making Node.js lightweight and scalable.

3. Fast Performance

The V8 engine compiles JavaScript directly into machine code, making Node.js extremely fast.

4. NPM (Node Package Manager)

NPM is the world’s largest software registry.
You can install thousands of ready-to-use packages with one command:

5. Cross-Platform

Run Node.js on Windows, Linux, or macOS without any issues.

Where is Node.js Used?

Backend web development
REST APIs & Microservices
Real-time chat apps
Multiplayer games
Streaming platforms
Cloud-native apps
DevOps tools
Automation scripts

Companies using Node.js:

Netflix
PayPal
LinkedIn
Uber
Walmart

Basic Example: Node.js Web Server

const http = require('http');

const server = http.createServer((req, res) => {
res.writeHead(200, { 'Content-Type': 'text/plain' });
res.end('Hello from Node.js Server!');
});

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

const http = require('http');

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

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

res.end('Hello from Node.js Server!');

});

server.listen(3000, () => {

console.log('Server is running on http://localhost:3000');

});

Run it:

Advantages of Node.js

Fast and efficient
Handles many connections at once
Great for real-time apps
Rich ecosystem of packages
Easy for JavaScript developers

Disadvantages of Node.js

Not suitable for CPU-heavy tasks
Callback hell (solved using Promises & async/await)
Single-threaded may limit complex calculations

Node.js Introduction