Node.js Basic to Advance Blog

Node.js Tutorial: From Basic to Advance

Everything you need to become a Node.js Developer

🚀 Introduction to Node.js

Node.js is an open-source, cross-platform JavaScript runtime environment that allows you to run JavaScript code outside a web browser. It's widely used for building scalable network applications.

⚙️ Installation & Setup

Download Node.js from nodejs.org. Use the terminal/command prompt to check installation:

node -v
npm -v

📦 Node.js Core Modules

fs – File system operations
http – Create HTTP servers
https – HTTPS servers with SSL/TLS
path – Handle and transform file paths
url – Parse and format URLs
querystring – Parse and stringify URL query strings
events – Event-driven programming with EventEmitter
stream – Streaming data processing (read/write)
os – Operating system-related utility methods
crypto – Cryptographic operations (hashing, encryption)
zlib – Compression and decompression (gzip, deflate)
util – Utility functions (promisify, inherits, etc.)
timers – Scheduling functions like setTimeout, setInterval
dns – DNS lookup and hostname resolution
net – Low-level networking (TCP/IPC)
child_process – Spawn and manage child processes
process – Provides info and control over the current Node process
readline – Read data from readable streams line by line
buffer – Handling binary data
console – Console logging functions (console.log, etc.)
v8 – Interact with the V8 engine internals
assert – Assertion testing for validating invariants
cluster – Run multiple instances of Node.js for load balancing
tty – Support for terminal I/O (used in REPL)
repl – Read-Eval-Print Loop for interactive console
module – Internal module loader (advanced use)

📁 Recommended Project Structure

project/
├── node_modules/
├── public/
├── src/
│   ├── controllers/
│   ├── models/
│   ├── routes/
│   ├── middlewares/
│   └── utils/
├── .env
├── package.json
└── server.js

This structure helps keep the code organized and scalable.

🌐 Express.js Framework

Express is a minimal and flexible Node.js web application framework that provides a robust set of features to develop web and mobile applications.

const express = require('express');
const app = express();

app.get('/', (req, res) => {
  res.send('Hello from Express!');
});

app.listen(3000);

🧩 Middleware in Node.js

Middleware functions are functions that have access to the request object, the response object, and the next middleware function in the application’s request-response cycle.

🔐 Authentication & Authorization

Authentication can be handled using libraries like passport.js or jsonwebtoken (JWT). Implement secure routes and protect sensitive data.

📁 File Uploads in Node.js

Use libraries like multer to handle file uploads. It helps parse multipart/form-data requests.

📡 Real-Time Communication with Socket.io

Build real-time features like chat apps using socket.io that leverages WebSockets.

🗄️ Using Databases (MySQL, MongoDB)

Connect Node.js to databases using:

MongoDB: via Mongoose
MySQL: via mysql2 or sequelize ORM

💡 Best Practices

Use environment variables with dotenv
Validate input with Joi or zod
Use try-catch with async/await
Follow proper folder structure
Write unit tests using Jest or Mocha

❓ Node.js Interview Questions (Basic to Advanced)

What is Node.js and how does it work?
Explain the event-driven architecture of Node.js.
What is the difference between synchronous and asynchronous programming?
What are Node.js core modules? Name a few.
How does the event loop work in Node.js?
What is npm and what is it used for?
How do you create a simple HTTP server in Node.js?
What is Express.js and why is it used?
Explain middleware in Express.js.
How do you handle file uploads in Node.js?
What is a callback function and how is it used in Node?
What is the purpose of `require()` in Node.js?
How can you connect Node.js to a MongoDB or MySQL database?
Explain error handling in Node.js.
What is JWT and how is it used in authentication?
What is the difference between `process.nextTick()`, `setImmediate()`, and `setTimeout()`?
How does clustering work in Node.js?
How would you secure a Node.js application?
What are Streams in Node.js?
How does real-time communication work with Socket.io?

🍃 MongoDB Interview Questions (Basic to Advanced)

What is MongoDB and how is it different from SQL databases?
What are Documents and Collections in MongoDB?
What is BSON?
How do you create a database and collection in MongoDB?
Explain CRUD operations in MongoDB with examples.
What is the _id field in MongoDB?
How do indexes work in MongoDB?
What is aggregation in MongoDB?
Difference between $match, $group, and $project in aggregation pipeline?
What are embedded documents and when to use them?
How do you perform joins in MongoDB?
What is a replica set?
What is sharding and why is it used?
Difference between find() and findOne()
How do you perform pagination in MongoDB?
What are schema validations in MongoDB?
Explain the role of MongoDB Atlas.
How do you secure MongoDB in production?
What is the difference between MongoDB and Mongoose?
What are transactions in MongoDB and how are they used?

🚀 Express.js Interview Questions

What is Express.js and why is it used?
How do you install and set up Express?
What are the main features of Express.js?
What is middleware in Express.js?
Difference between application-level and router-level middleware?
How do you define routes in Express?
How do you handle 404 and error middleware in Express?
What are the different HTTP methods supported by Express?
How do you parse incoming request bodies?
How can you handle file uploads in Express?
How to connect a MongoDB/Mongoose model in Express?
What is the use of `express.static()`?
How to handle route parameters and query strings?
What is `req` and `res` in Express?
How do you implement JWT authentication in Express?
How to structure a large Express application?
What are CORS and how do you enable them in Express?
How do you protect routes in Express?
How can you create and use routers in Express?
Difference between `app.use()` and `app.get()`?

🧠 Node.js Advanced Interview Questions (5+ Years Experience)

Explain the Node.js event loop in detail. How does it handle async I/O?
How does Node.js achieve non-blocking I/O using libuv?
What are the performance bottlenecks in a Node.js application and how do you resolve them?
How would you scale a Node.js application across multiple CPU cores?
What is clustering in Node.js and when should you use it?
How do you handle memory leaks in Node.js?
How would you implement caching in a high-traffic Node.js API?
What are Streams in Node.js and how do they improve performance?
How do you secure a Node.js REST API in production?
What are worker threads and when should you use them over clustering?
Explain the difference between process.nextTick(), setImmediate(), and setTimeout().
How would you implement rate limiting in a Node.js application?
What’s the difference between synchronous and asynchronous error handling in Node.js?
How do you implement logging in a production Node.js app?
What is load balancing and how can it be used with Node.js apps?
Explain the architecture of your last enterprise-level Node.js project.
What tools do you use for profiling and monitoring Node.js apps in production?
How do you ensure graceful shutdown in a Node.js app?
How does garbage collection work in Node.js?
What are some anti-patterns in Node.js and how do you avoid them?

✅ Conclusion

Node.js is powerful for building backend services, APIs, real-time applications, and even automation scripts. Continue exploring modules, tools, and best practices to become a full-stack Node.js developer.