🚀 Backend with Node.js

A complete, hands-on journey through backend development with Node.js & Express

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📖 About This Repository

This repository is a structured learning journey through backend development using Node.js. Starting from the very basics of how Node.js works under the hood, all the way up to building a real-world Spotify-like backend with JWT authentication, role-based access control, and cloud file uploads.

Each folder represents a milestone — a new concept learned, a new skill unlocked. 🎯

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🗂️ Folder Structure

Backend/
│
├── 📁 Basic/                    → Node.js fundamentals (modules, fs, CommonJS)
│   ├── hello.js                 → First Node.js script, require() & destructuring
│   ├── math.js                  → Creating & exporting custom modules
│   ├── file.js                  → File System (fs) — sync vs async operations
│   ├── contact.txt              → Sample file used in fs read/write demos
│   └── test.txt                 → Output file for appendFileSync demo
│
├── 📁 server/                   → Raw HTTP server (no frameworks!)
│   ├── index.js                 → http.createServer(), URL parsing, routing, logging
│   ├── log.txt                  → Auto-generated request log
│   └── url_data.txt             → Parsed URL query data
│
├── 📁 Express/                  → Introduction to Express.js
│   └── index.js                 → Routes, query parameters, req/res lifecycle
│
├── 📁 HTTP_methods(api)/        → REST HTTP methods with Express (in-memory)
│   └── src/
│       └── app.js               → GET, POST, DELETE routes with dynamic params
│
├── 📁 Rest_api/                 → Full REST API with file-based persistence
│   ├── index.js                 → CRUD operations, middleware, routing patterns
│   └── MOCK_DATA.json           → 1000+ mock user records (seed data)
│
├── 📁 Mongodb/                  → MongoDB + Mongoose integration
│   ├── server.js                → Entry point — connects DB and starts server
│   ├── models/
│   │   └── note.model.js        → Mongoose schema & model definition
│   ├── database/
│   │   └── db.js                → MongoDB connection using Mongoose
│   └── src/
│       └── app.js               → Notes CRUD API with async/await + error handling
│
├── 📁 Authenciation/            → JWT Authentication from scratch
│   ├── server.js                → Entry point
│   └── src/
│       ├── app.js               → App setup with routes and cookie-parser
│       ├── db/db.js             → DB connection
│       ├── model/
│       │   └── user.model.js    → User schema (username, email, password)
│       ├── controllers/
│       │   └── auth.controller.js  → Register user + JWT token in cookie
│       └── routes/
│           ├── auth.route.js    → /api/auth routes
│           └── post.route.js    → Protected route — cookie/token verification
│
├── 📁 spotify_backend/          → 🎵 Capstone Project — Spotify-like Backend
│   ├── server.js                → Entry point with dotenv validation
│   └── src/
│       ├── app.js               → Express app with auth & music routes
│       ├── db/db.js             → MongoDB connection
│       ├── models/
│       │   ├── user.model.js    → User with role (user | artist)
│       │   ├── music.model.js   → Music with audioUrl, title, artist ref
│       │   └── album.model.js   → Album with title, artist, music refs
│       ├── controllers/
│       │   ├── auth.controller.js   → Register, Login, Logout with bcrypt
│       │   └── music.controller.js  → Upload music, create album, fetch all
│       ├── middlewares/
│       │   └── auth.middleware.js   → authArtist & authUser JWT middleware
│       ├── routes/
│       │   ├── auth.route.js    → /api/auth routes
│       │   └── music.route.js   → /api/music routes (protected)
│       └── services/
│           └── storage.service.js   → ImageKit cloud upload service
│
└── 📁 Project1/                 → Additional project workspace
    ├── Backend/
    └── Frontend/

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⚡ Concepts Covered

🟢 Chapter 1 — Node.js Basics (Basic/)

Concept	What You Learned
CommonJS Modules	require(), module.exports, exports. shorthand
Module Destructuring	const { add, sub } = require('./math')
File System (fs)	Sync vs Async — readFileSync, readFile, writeFile, appendFileSync
Callbacks	How async fs methods use (err, result) callbacks

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🌐 Chapter 2 — Raw HTTP Server (server/)

Concept	What You Learned
http module	http.createServer(), handler functions
URL Parsing	url.parse(req.url, true) — extracting pathname & query params
Manual Routing	switch/case on myurl.pathname
HTTP Methods	Checking req.method (GET vs POST) on same route
Request Logging	Appending timestamps + URLs to a log file asynchronously

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🚂 Chapter 3 — Express.js (Express/)

Concept	What You Learned
Express App	const app = express() — how it wraps the http module
Route Handlers	app.get(path, handler) — cleaner routing
Query Parameters	req.query.name, req.query.age
Sending Responses	res.send(), dynamic string responses

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🔧 Chapter 4 — HTTP Methods & REST (HTTP_methods(api)/ & Rest_api/)

Concept	What You Learned
GET	Fetch all or a single resource
POST	Create a new resource via req.body
PATCH	Partially update an existing resource
DELETE	Remove a resource by ID or index
Dynamic Route Params	app.get('/users/:id') → req.params.id
Middleware	app.use(), express.json(), express.urlencoded(), custom middleware
Middleware Chain	next() — how middleware passes control down the chain
File Persistence	Writing updated JSON data back to disk with fs.writeFileSync
app.route()	Chaining .get().patch().delete() on the same path

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🍃 Chapter 5 — MongoDB & Mongoose (Mongodb/)

Concept	What You Learned
MongoDB Connection	mongoose.connect() with async/await
Schema Definition	new mongoose.Schema({ title: String, description: String })
Model Creation	mongoose.model('note', noteSchema)
CRUD with Mongoose	.create(), .find(), .findByIdAndUpdate(), .findByIdAndDelete()
Async/Await + Try/Catch	Clean async error handling in route handlers
HTTP Status Codes	201, 200, 404, 500 — using them correctly

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🔐 Chapter 6 — JWT Authentication (Authenciation/)

Concept	What You Learned
JWT Signing	JWT.sign({ id: user._id }, process.env.JWT_SECRET)
Cookies	res.cookie('token', token) — storing JWT in HTTP cookie
Cookie Parser	cookie-parser middleware — req.cookies.token
Protected Routes	Verifying JWT before allowing access to a route
JWT Verify	JWT.verify(token, secret) — decoding and validating the token
Environment Variables	dotenv — keeping secrets out of code with .env files
MVC Pattern	Splitting routes → controllers → models into separate files

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🎵 Chapter 7 — Capstone: Spotify Backend (spotify_backend/)

Concept	What You Learned
bcryptjs	Hashing passwords with bcrypt.hash() before saving to DB
Password Comparison	bcrypt.compare(plain, hashed) — safe login verification
Role-Based Access Control	User roles (user, artist) enforced via JWT payload
Auth Middleware	authArtist & authUser — role-check before route execution
Req Mutation	Setting req.user = decoded in middleware for downstream use
Mongoose Population	.populate('artist', 'username email') — joining documents
Mongoose .select()	Returning only specific fields from a query
Pagination/Limiting	.limit(20) — preventing memory overload
File Uploads (Multer)	Handling multipart/form-data for audio file upload
Cloud Storage (ImageKit)	Uploading audio buffers to ImageKit CDN
Mongoose Refs	Linking models with type: mongoose.Schema.Types.ObjectId, ref: 'User'
Logout	res.clearCookie('token') — invalidating session
$or Query Operator	Checking multiple fields in one MongoDB query

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🛠️ Setup & Installation

Prerequisites

Make sure you have the following installed:

• Node.js (v18 or higher recommended)
• npm (comes with Node.js)
• MongoDB — local or MongoDB Atlas (cloud)
• Postman or Thunder Client (VS Code extension) — for testing APIs

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🚀 Running Any Module

Each subfolder is its own mini-project. Navigate to the folder and install dependencies:

# Example: Running the Express server
cd Express
npm install
node index.js

# Example: Running the REST API
cd Rest_api
npm install
node index.js

# Example: Running MongoDB project
cd Mongodb
npm install
node server.js

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🔑 Environment Variables Setup

For modules that use MongoDB, JWT, or ImageKit, create a .env file in the respective folder:

Authenciation/.env

MONGO_URI=mongodb+srv://<username>:<password>@cluster.mongodb.net/authDB
JWT_SECRET=your_super_secret_key_here
PORT=3000

Mongodb/.env

MONGO_URI=mongodb+srv://<username>:<password>@cluster.mongodb.net/notesDB

spotify_backend/.env

MONGO_URI=mongodb+srv://<username>:<password>@cluster.mongodb.net/spotifyDB
JWT_SECRET=your_super_secret_key_here
IMAGEKIT_PUBLIC_KEY=your_imagekit_public_key
IMAGEKIT_PRIVATE_KEY=your_imagekit_private_key
IMAGEKIT_URL_ENDPOINT=https://ik.imagekit.io/your_id
PORT=3000

⚠️ Never commit your .env file to Git! The .gitignore in this repo already excludes it.

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🎵 Running the Spotify Backend (Capstone Project)

cd spotify_backend
npm install
# Make sure your .env file is configured
node server.js

API Endpoints:

Method	Endpoint	Access	Description
POST	/api/auth/register	Public	Register a new user or artist
POST	/api/auth/login	Public	Login and receive JWT cookie
POST	/api/auth/logout	Public	Clear JWT cookie
POST	/api/music/upload	Artist only	Upload a music track
POST	/api/music/album	Artist only	Create a new album
GET	/api/music/all	User + Artist	Fetch all music (limit 20)
GET	/api/music/albums	User + Artist	Fetch all albums
GET	/api/music/albums/:albumId	User + Artist	Get album by ID

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📦 Key Dependencies Used

Package	Purpose
express	Web framework — routing, middleware
mongoose	MongoDB ODM — schemas, models, queries
jsonwebtoken	JWT creation and verification
bcryptjs	Secure password hashing
cookie-parser	Parse HTTP cookies from req.cookies
dotenv	Load environment variables from .env
multer	Handle multipart file uploads
@imagekit/nodejs	Upload files to ImageKit CDN

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💡 Learning Path

Node.js Basics  →  Raw HTTP Server  →  Express.js  →  REST API  →  MongoDB  →  JWT Auth  →  Spotify Backend
     📦                  🌐               🚂              🔧           🍃          🔐              🎵

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👨‍💻 Author

Himanshu — Learning backend development, one concept at a time. 🚀

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Built with ❤️ and lots of console.log() 😄