Interview Q&A

Short answer: express-validator Joi yup zod All support schema-based and custom validations.

Real-world example (ShopNest)

Express middleware authenticates JWT, then the /orders route handler creates the order.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Uses semantic versioning: MAJOR.MINOR.PATCH. New major versions can include breaking changes.

Real-world example (ShopNest)

A ShopNest BFF in Node.js aggregates catalog and price APIs for the React storefront.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: ll support schema-based and custom validations.

Real-world example (ShopNest)

Express middleware authenticates JWT, then the /orders route handler creates the order.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Typical options include: JWT tokens OAuth API keys Sessions (less common for APIs) 📌 Usually, the client includes a token in the Authorization header: Authorization: Bearer <token> The server verifies the token on every request.

Real-world example (ShopNest)

A ShopNest BFF in Node.js aggregates catalog and price APIs for the React storefront.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: npm: Default Node package manager. yarn: Faster installs, better caching. pnpm: Efficient disk usage by linking packages.

Real-world example (ShopNest)

A ShopNest BFF in Node.js aggregates catalog and price APIs for the React storefront.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: uthorization: Bearer <token> The server verifies the token on every request.

Real-world example (ShopNest)

A ShopNest BFF in Node.js aggregates catalog and price APIs for the React storefront.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Babel: Transpiles modern JS to compatible versions. TypeScript: Adds static typing and compiles to JS.

Real-world example (ShopNest)

A ShopNest BFF in Node.js aggregates catalog and price APIs for the React storefront.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: JWT (JSON Web Token) is a compact, URL-safe token used for securely transmitting information. Consists of Header, Payload, and Signature Used to verify user identity and permissions 📌 Generate: const jwt = require('jsonwebtoken'); const token = jwt.sign({ id: user.id }, 'secret', { expiresIn: '1h' }); 📌 Verify: jwt.verify(token, 'secret');

Real-world example (ShopNest)

A ShopNest BFF in Node.js aggregates catalog and price APIs for the React storefront.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Use the multer middleware: npm install multer 📌 Example: const multer = require('multer'); const upload = multer({ dest: 'uploads/' }); app.post('/upload', upload.single('file'), (req, res) => { res.send('File uploaded'); });

Example code

Use the multer middleware: npm install multer 📌 Example: const multer = require('multer');
const upload = multer({ dest: 'uploads/' }); app.post('/upload', upload.single('file'), (req, res) => { res.send('File uploaded'); });

Real-world example (ShopNest)

A ShopNest BFF in Node.js aggregates catalog and price APIs for the React storefront.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: pp.post('/upload', upload.single('file'), (req, res) => { res.send('File uploaded'); }); pp.post('/upload', upload.single('file'), (req, res) => { res.send('File uploaded'); }); pp.post('/upload', upload.single('file'), (req, res) => { res.send('File uploaded'); }); pp.post('/upload', upload.single('file'), (req, res) => { res.send('File uploaded'); });

Real-world example (ShopNest)

A ShopNest BFF in Node.js aggregates catalog and price APIs for the React storefront.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Use testing frameworks: Jest or Mocha for unit tests Supertest for HTTP API testing 📌 Example with Supertest: const request = require('supertest'); request(app) .get('/api/users') .expect(200) .then(res => { console.log(res.body); });

Real-world example (ShopNest)

A ShopNest BFF in Node.js aggregates catalog and price APIs for the React storefront.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Rate limiting prevents abuse by limiting the number of requests a user can make in a given time. 📌 Use express-rate-limit: npm install express-rate-limit const rateLimit = require('express-rate-limit'); const limiter = rateLimit({ windowMs: 15 * 60 * 1000, max: 100 // limit per IP }); app.use(limiter);

Real-world example (ShopNest)

A ShopNest BFF in Node.js aggregates catalog and price APIs for the React storefront.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Use the morgan middleware: npm install morgan const morgan = require('morgan'); app.use(morgan('dev')); Logs every request with method, status, time, etc.

Example code

Use the morgan middleware: npm install morgan const morgan = require('morgan'); app.use(morgan('dev')); Logs every request with method, status, time, etc.

Real-world example (ShopNest)

A ShopNest BFF in Node.js aggregates catalog and price APIs for the React storefront.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: pp.use(morgan('dev')); Logs every request with method, status, time, etc. pp.use(morgan('dev')); Logs every request with method, status, time, etc. pp.use(morgan('dev')); Logs every request with method, status, time, etc. pp.use(morgan('dev')); Logs every request with method, status, time, etc.

Real-world example (ShopNest)

A ShopNest BFF in Node.js aggregates catalog and price APIs for the React storefront.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Use plural nouns in endpoints (/users, not /user) Use proper HTTP methods Send meaningful status codes Keep URLs simple and consistent Use pagination for large data Protect with authentication/authorization Use versioning (/api/v1/...) Validate and sanitize all inputs NPM and module-related Node.js interview questions

Real-world example (ShopNest)

A ShopNest BFF in Node.js aggregates catalog and price APIs for the React storefront.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.