Node.js Get Started

Node.js – Get Started

What • Why • Installation • First App • How It Works • Next Steps

Node.js lets you run JavaScript outside the browser.
You can build fast servers, APIs, real-time apps, and scalable backend systems using only JavaScript.

One-line idea

Node.js = JavaScript on the server

1️⃣ What is Node.js?

Node.js is a JavaScript runtime environment built on V8 JavaScript Engine.

It allows JavaScript to run on:

Servers
PCs
APIs
Backend systems

Before Node.js → JavaScript worked only in browsers
After Node.js → JavaScript works everywhere

2️⃣ Why Use Node.js?

✔ Very fast (non-blocking, event-driven)
✔ Same language for frontend & backend
✔ Handles thousands of requests easily
✔ Huge ecosystem via npm
✔ Used by Netflix, Uber, PayPal, LinkedIn

3️⃣ How Node.js Works (Simple Explanation)

Node.js uses:

Single Thread
Non-blocking I/O
Event Loop

Instead of waiting for one task to finish, Node.js keeps working and handles results asynchronously.

4️⃣ Install Node.js (Step-by-Step)

Step 1: Download

Visit 👉 https://nodejs.org
Choose: LTS (Recommended for beginners)

Step 2: Install

Windows → Next → Next → Install
macOS → .pkg file
Linux → Package manager

Step 3: Verify Installation

If versions appear → Installation successful

5️⃣ Your First Node.js Program

Create a file: app.js

Run:

Output

6️⃣ Create a Simple 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 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 running on http://localhost:3000");

});

👉 Open browser: http://localhost:3000

7️⃣ What is npm?

npm (Node Package Manager)
Used to install libraries & tools.

Examples:

npm has 1M+ packages

8️⃣ Popular Node.js Use Cases

✔ REST APIs

✔ Web servers
✔ Real-time chat apps
✔ Streaming platforms
✔ Microservices
✔ IoT backends

9️⃣ Node.js vs Other Backend Languages

Feature	Node.js	PHP / Java
Language	JavaScript	PHP / Java
Speed	Very Fast	Moderate
Scalability	High	Medium
Real-time Apps	Excellent	Harder

🔟 Basic Folder Structure

node_modules → Installed packages
package.json → Project info & dependencies

Running JS without node filename.js
Confusing Node.js with browser JavaScript

Common Beginner Mistakes

❌ Forgetting to install Node.js❌ Writing blocking code (heavy loops, sleep)

Final Summary

✔ Node.js runs JavaScript on the server
✔ Fast, scalable & event-driven
✔ Uses npm for packages
✔ Ideal for APIs & real-time apps
✔ Must-know skill for modern web developers

Node.js Get Started