Web Development

🧠 199. What is Babel?

Babel is a JavaScript compiler that converts modern JavaScript into browser-compatible JavaScript.

Example:

Modern JS: const greet = () => { console.log("Hello") }

Converted to older JS that older browsers understand.

Benefits:

✅ Browser compatibility

✅ Support for modern JavaScript features

🧠 200. What is TypeScript and Why Use It?

TypeScript is a superset of JavaScript developed by Microsoft.

It adds: Static typing, Interfaces, Better tooling

JS: let age = 25

TS: let age: number = 25

Benefits:

✅ Fewer bugs

✅ Better code quality

✅ Improved IntelliSense

✅ Easier maintenance

🔥 Advanced Web Development Questions Frequently Asked in Interviews

Performance Optimization

1. What is Lazy Loading

2. What is Code Splitting

3. What is Tree Shaking

4. How can you improve website performance

5. What is caching

PWA

1. What is PWA

2. What are Service Workers

3. How does offline support work

React & Next.js

1. What is SSR

2. What is CSR

3. Difference between SSR and CSR

4. What is Hydration

5. Why use Next.js

Build Tools

1. What is Webpack

2. What is Babel

3. What is Vite

4. What is Parcel

TypeScript

1. What is TypeScript

2. Difference between TypeScript and JavaScript

3. Why do companies prefer TypeScript

Before attending a Web Development interview, make sure you're comfortable with:

✅ HTML5 & Semantic Tags

✅ CSS Flexbox & Grid

✅ JavaScript ES6+ Concepts

✅ DOM Manipulation

✅ React Hooks & State Management

✅ Node.js & Express.js

✅ SQL & MongoDB

✅ REST APIs & Authentication

✅ Git & GitHub

✅ Web Security Concepts

✅ Docker & Cloud Basics

✅ TypeScript Fundamentals

✅ Performance Optimization Techniques

🔥 Double Tap ❤️ For Part-10

🚀 Web Development Interview Questions with Answers — Part 10: Advanced Web Development

🧠 191. What is a Progressive Web App (PWA)?

A Progressive Web App (PWA) is a web application that provides an app-like experience in a browser.

Features:

✅ Works offline

✅ Fast loading

✅ Installable on devices

✅ Push notifications

✅ Responsive design

Examples: Twitter Lite, Pinterest, Starbucks PWA

Benefits:

No app store required

Better performance

Improved user engagement

🧠 192. What is a Service Worker?

A Service Worker is a JavaScript file that runs in the background independently of a webpage.

Responsibilities:

Caching resources

Offline support

Push notifications

Background sync

Example:

navigator.serviceWorker.register("/service-worker.js")

Benefits:

✅ Offline access

✅ Faster page loading

✅ Better user experience

🧠 193. What is Lazy Loading?

Lazy loading means loading resources only when they are needed.

Examples: Images, Components, Videos

React Example:

const Home = React.lazy(() => import("./Home"))

Benefits:

✅ Faster initial page load

✅ Better performance

✅ Reduced bandwidth usage

🧠 194. What is Code Splitting?

Code splitting divides a large JavaScript bundle into smaller chunks.

Example:

Instead of loading: app.js = 5 MB

Load: home.js, profile.js, dashboard.js

Benefits:

✅ Faster loading

✅ Better performance

✅ Smaller bundles

🧠 195. What is Tree Shaking?

Tree shaking removes unused code from final production bundles.

Example: import { add } from "./math"

Unused functions are removed during build.

Benefits:

✅ Smaller bundle size

✅ Faster application

🧠 196. What is SSR in Next.js?

SSR stands for: Server-Side Rendering

In SSR, HTML is generated on the server before being sent to the browser.

Benefits:

✅ Better SEO

✅ Faster initial page load

✅ Improved performance

Flow: Browser → Server → Rendered HTML → Browser

🧠 197. What is Hydration in React?

Hydration is the process where React attaches event handlers to server-rendered HTML.

Flow: Server Render HTML → Browser Loads HTML → React Adds Interactivity

Benefits: ✅ Interactive pages, ✅ Better user experience

🧠 198. What is Webpack?

Webpack is a module bundler that combines project files into optimized bundles.

Responsibilities:

Bundling files

Minification

Code splitting

Asset optimization

Example:

module.exports = {
   entry: "./src/index.js"
}

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🧠 189. What is Cloud Hosting?

Cloud hosting means hosting applications on cloud servers rather than physical servers.

Benefits:

✅ Scalability

✅ High availability

✅ Pay-as-you-go pricing

Popular Cloud Providers:

AWS

Microsoft Azure

Google Cloud Platform

🧠 190. Difference Between AWS, Azure, and GCP

Cloud | AWS | Azure | GCP

Position | Market leader | Strong Microsoft integration | Strong AI & Analytics

Focus | Largest service portfolio | Enterprise-focused | Developer-friendly

Popularity | Most popular cloud platform | Popular in enterprises | Strong data services

AWS Popular Services:

EC2

S3

RDS

Lambda

Azure Popular Services:

Virtual Machines

Azure SQL

Azure Functions

GCP Popular Services:

Compute Engine

BigQuery

Cloud Functions

🔥 Frequently Asked DevOps Interview Questions

Git

1. What is Git?

2. What is GitHub?

3. What is branching?

4. What is rebasing?

5. What is merge conflict?

CI/CD

1. What is CI/CD?

2. Why is CI/CD important?

3. Explain deployment pipeline.

Docker

1. What is Docker?

2. Difference between container and virtual machine?

Kubernetes

1. What is Kubernetes?

2. What is a Pod?

3. What is a Deployment?

4. What is a Service in Kubernetes?

Cloud

1. What is cloud computing?

2. What is AWS?

3. What is Azure?

4. What is GCP?

5. What is serverless computing?

6. What is auto-scaling?

🎯 Interview Tip

For Full Stack Developer interviews, focus heavily on:

✅ Git & GitHub

✅ REST APIs

✅ Docker Basics

✅ CI/CD Concepts

✅ Cloud Fundamentals (AWS/Azure/GCP)

✅ Deployment Process

✅ Linux Commands

✅ Environment Variables

🔥 Double Tap ❤️ For Part-9

🚀 Web Development Interview Questions with Answers — Part 9: Deployment, DevOps & Cloud

🧠 181. What is Git?

Git is a distributed version control system used to track code changes.

Benefits:

✅ Track code history

✅ Collaborate with teams

✅ Manage versions

Example:

git init

🧠 182. Difference Between Git and GitHub

Concept | Git | GitHub

Version control system | Cloud hosting platform

Works locally | Works online

Tracks code changes | Stores repositories

Example:

Git : Local machine

GitHub : Remote repository hosting

🧠 183. What is Version Control?

Version control is a system that records changes to files over time.

Benefits:

✅ Roll back changes

✅ Team collaboration

✅ Change tracking

Example:

git log

🧠 184. What is Branching in Git?

A branch is an independent line of development.

Common Branches:

main

develop

feature branches

Example:

git branch feature-login

Benefits:

✅ Safe development

✅ Parallel work

🧠 185. What is a Merge Conflict?

A merge conflict occurs when Git cannot automatically merge changes.

Example:

Two developers modify the same line of code.

Resolution Steps:

1. Identify conflict

2. Edit conflicting code

3. Commit changes

git add .
git commit

🧠 186. What is CI/CD?

CI/CD stands for:

👉 Continuous Integration (CI)

👉 Continuous Deployment/Delivery (CD)

Continuous Integration:

Automatically tests code after every commit.

Continuous Deployment:

Automatically deploys code after successful testing.

Benefits:

✅ Faster releases

✅ Reduced bugs

✅ Automation

🧠 187. What is Docker?

Docker is a platform used to package applications into containers.

Benefits:

✅ Consistent environments

✅ Easy deployment

✅ Lightweight containers

Example:

docker build .

Container Example:

Application

Dependencies

Libraries

Configuration

All packaged together.

🧠 188. What is Kubernetes?

Kubernetes is a container orchestration platform.

It manages:

Containers

Scaling

Load balancing

Deployments

Benefits:

✅ Auto-scaling

✅ High availability

✅ Container management

Example:

kubectl get pods

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🧠 179. What is CDN?

CDN stands for: 👉 Content Delivery Network

A CDN stores copies of content across multiple servers worldwide.

Benefits:

✅ Faster content delivery

✅ Reduced latency

✅ Better availability

Examples:

Cloudflare

Akamai

🧠 180. What is Load Balancing?

Load balancing distributes traffic across multiple servers.

Example:

Users

↓

Load Balancer

↓ ↓ ↓

Server1 Server2 Server3

Benefits:

✅ High availability

✅ Better performance

✅ Fault tolerance

🔥 Double Tap ❤️ For Part-8

🚀 Web Development Interview Questions with Answers — Part 8: APIs & Backend Concepts

🧠 166. What is an API?

API stands for: 👉 Application Programming Interface

An API allows different software applications to communicate with each other.

Example:

When a weather app fetches weather data from a server, it uses an API.

Benefits:

✅ Data sharing

✅ System integration

✅ Automation

🧠 167. Difference Between REST and GraphQL

Concept | REST | GraphQL

Endpoints | Multiple endpoints | Single endpoint

Response structure | Fixed response structure | Client chooses data

Data fetching | Over-fetching possible | Fetch only needed data

Complexity | Simpler | More flexible

Example:

REST: GET /users/1

GraphQL:

{
  user(id:1){
    name
    email
  }
}

🧠 168. What is a RESTful API?

RESTful API follows REST architectural principles.

Key Principles:

Stateless

Client-Server Architecture

Uniform Interface

Resource-Based URLs

Example:

GET /users

POST /users

PUT /users/1

DELETE /users/1

🧠 169. What are HTTP Status Codes?

HTTP status codes indicate server response status.

Categories:

Range | Meaning

1xx | Informational

2xx | Success

3xx | Redirection

4xx | Client Error

5xx | Server Error

🧠 170. Explain 200, 201, 400, 401, 403, 404, and 500

Code | Meaning

200 | OK

201 | Created

400 | Bad Request

401 | Unauthorized

403 | Forbidden

404 | Not Found

500 | Internal Server Error

Example:

res.status(404).json({
   message: "User Not Found"
});

🧠 171. What is API Testing?

API Testing verifies functionality, performance, and security of APIs.

Checks:

✅ Response data

✅ Status codes

✅ Authentication

✅ Performance

Tools:

Postman

Insomnia

Swagger

🧠 172. What is Postman?

Postman is a tool used to test APIs.

Features:

✅ Send API requests

✅ Test endpoints

✅ Automate testing

✅ Manage collections

Example:

GET https://api.example.com/users

🧠 173. What is WebSocket?

WebSocket enables real-time two-way communication between client and server.

Uses:

Chat applications

Online gaming

Live notifications

Stock market updates

Benefits:

✅ Real-time communication

✅ Low latency

🧠 174. Difference Between Polling and WebSocket

Concept | Polling | WebSocket

Connection | Client repeatedly asks server | Persistent connection

Network usage | Higher network usage | Efficient communication

Updates | Slower updates | Real-time updates

🧠 175. What is Microservice Architecture?

Microservices divide an application into small independent services.

Example:

User Service

Payment Service

Order Service

Notification Service

Benefits:

✅ Scalability

✅ Independent deployment

✅ Easier maintenance

🧠 176. What is Monolithic Architecture?

Monolithic architecture combines all components into one application.

Example:

Frontend

Backend

Database

↓

Single Application

Advantages:

✅ Simpler development initially

Disadvantages:

❌ Harder to scale

🧠 177. What is Caching?

Caching stores frequently accessed data temporarily for faster retrieval.

Benefits:

✅ Faster performance

✅ Reduced database load

✅ Improved user experience

Example:

cache.set("users", data);

🧠 178. What is Redis?

Redis is an in-memory database commonly used for caching.

Features:

✅ Extremely fast

✅ Key-value storage

✅ Session management

Example:

redis.set("user", userData);

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Benefits:

✅ Prevents malicious scripts

✅ Improves website security

🧠 164. What is Brute Force Attack?

A brute force attack tries many password combinations until the correct one is found.

Prevention:

✅ Strong passwords

✅ Account lockout

✅ Rate limiting

✅ Multi-factor authentication

🧠 165. What is Two-Factor Authentication (2FA)?

2FA requires two forms of verification before granting access.

Example:

1. Password

2. OTP sent to phone

Benefits:

✅ Enhanced security

✅ Reduced account compromise risk

Double Tap ❤️ For Part-8

🚀 Web Development Interview Questions with Answers — Part 7: Web Security

🧠 151. What is HTTPS?

HTTPS stands for: 👉 HyperText Transfer Protocol Secure

It is the secure version of HTTP that encrypts data exchanged between browser and server.

Benefits:

✅ Secure communication

✅ Protects sensitive data

✅ Prevents eavesdropping

Example: https://example.com

🧠 152. Difference Between HTTP and HTTPS

Feature : HTTP : HTTPS

Security : Not secure : Secure

Data : Sent as plain text : Data encrypted

Port : Uses Port 80 : Uses Port 443

SSL/TLS : No SSL/TLS : Requires SSL/TLS

🧠 153. What is SSL/TLS?

SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are protocols that encrypt data transmission.

Benefits:

✅ Data encryption

✅ Authentication

✅ Data integrity

Example: When you see a padlock icon in the browser, SSL/TLS is being used.

🧠 154. What is XSS Attack?

XSS stands for: 👉 Cross-Site Scripting

It occurs when attackers inject malicious JavaScript into webpages.

Example:

<script>
alert("Hacked");
</script>

Prevention:

✅ Validate input

✅ Escape output

✅ Use Content Security Policy (CSP)

🧠 155. What is CSRF Attack?

CSRF stands for: 👉 Cross-Site Request Forgery

It tricks authenticated users into performing unwanted actions.

Example: A logged-in user unknowingly submits a bank transfer request.

Prevention:

✅ CSRF Tokens

✅ SameSite Cookies

✅ Authentication checks

🧠 156. What is SQL Injection?

SQL Injection occurs when malicious SQL code is inserted into queries.

Vulnerable Query:

SELECT * FROM users
WHERE username = 'admin'
AND password = '123';

Prevention:

✅ Prepared Statements

✅ Parameterized Queries

✅ Input Validation

🧠 157. How to Secure APIs?

Best Practices:

✅ Use HTTPS

✅ Authentication & Authorization

✅ Rate Limiting

✅ Input Validation

✅ API Keys

✅ JWT Tokens

Example: Authorization: Bearer <token>

🧠 158. What is Hashing?

Hashing converts data into a fixed-length value.

Example:

password123  
↓  
5e884898da...  

Uses: Password storage, Data verification

🧠 159. Difference Between Encryption and Hashing

Feature : Encryption : Hashing

Reversibility : Reversible : Irreversible

Key : Uses key : No key required

Purpose : Protects data : Verifies integrity

Example:

Encryption → Credit card data

Hashing → Passwords

🧠 160. What is bcrypt?

bcrypt is a password hashing algorithm.

Features:

✅ Salt generation

✅ Secure password storage

✅ Resistant to brute-force attacks

Example:

const hash = await bcrypt.hash(password, 10);

🧠 161. What is OAuth?

OAuth is an authorization framework that allows third-party applications to access resources without sharing passwords.

Examples: Login with Google, Login with GitHub, Login with Facebook

Benefits:

✅ Secure authentication

✅ No password sharing

🧠 162. What is JWT Token Security?

JWT (JSON Web Token) securely transmits user information.

Structure: Header.Payload.Signature

Security Tips:

✅ Short expiration time

✅ Use HTTPS

✅ Store securely

🧠 163. What is Content Security Policy (CSP)?

CSP is a browser security feature that helps prevent XSS attacks.

Example:

Content-Security-Policy: default-src 'self';

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Benefits:

✅ Easy database interaction

✅ Supports SQL databases

🧠 146. What is Mongoose?

Mongoose is an ODM library for MongoDB.

Example:

const User = mongoose.model("User", userSchema);

🧠 147. What are ACID Properties?

ACID ensures reliable database transactions.

Properties:

• Atomicity

• Consistency

• Isolation

• Durability

Benefits:

✅ Data reliability

✅ Transaction safety

🧠 148. What is Transaction?

Transaction is a group of database operations executed together.

Example:

BEGIN;

UPDATE accounts

SET balance = balance - 500

WHERE id = 1;

COMMIT;

🧠 149. What is Database Sharding?

Sharding splits database into smaller parts.

Benefits:

✅ Better scalability

✅ Faster performance

🧠 150. What is Replication?

Replication copies database data across multiple servers.

Benefits:

✅ High availability

✅ Backup support

✅ Fault tolerance

Double Tap ❤️ For Part-7

🚀 Web Development Interview Questions with Answers — Part 6: Database

🧠 131. What is SQL?

SQL stands for: 👉 Structured Query Language

It is used to manage and manipulate relational databases.

Uses:

• Store data

• Retrieve data

• Update records

• Delete records

Example:

SELECT * FROM users;

🧠 132. Difference Between SQL and NoSQL

SQL : Relational database : Uses tables : Structured schema

NoSQL : Non-relational database : Uses collections/documents : Flexible schema

Examples:

• SQL → MySQL

• NoSQL → MongoDB

🧠 133. What is Primary Key?

Primary key uniquely identifies each record in a table.

Features:

✅ Unique

✅ Cannot be NULL

Example:

CREATE TABLE users (

id INT PRIMARY KEY,

name VARCHAR(50)

);

🧠 134. What is Foreign Key?

Foreign key creates relationship between two tables.

Example:

CREATE TABLE orders (

order_id INT,

user_id INT,

FOREIGN KEY (user_id) REFERENCES users(id)

);

🧠 135. What is Normalization?

Normalization organizes database to reduce redundancy.

Normal Forms:

• 1NF

• 2NF

• 3NF

Benefits:

✅ Reduced duplication

✅ Better consistency

✅ Improved integrity

🧠 136. What are Joins in SQL?

Joins combine data from multiple tables.

Types:

• INNER JOIN

• LEFT JOIN

• RIGHT JOIN

• FULL JOIN

Example:

SELECT users.name, orders.amount

FROM users

INNER JOIN orders

ON users.id = orders.user_id;

🧠 137. Difference Between INNER JOIN and LEFT JOIN

INNER JOIN : Returns matching rows only

LEFT JOIN : Returns all left table rows

Example:

SELECT * FROM users

LEFT JOIN orders

ON users.id = orders.user_id;

🧠 138. What is Indexing?

Index improves database query performance.

Benefits:

✅ Faster searches

✅ Faster filtering

Example:

CREATE INDEX idx_name

ON users(name);

🧠 139. What is Aggregate Function?

Aggregate functions perform calculations on multiple rows.

Common Functions:

• COUNT()

• SUM()

• AVG()

• MIN()

• MAX()

Example:

SELECT COUNT(*) FROM users;

🧠 140. Difference Between DELETE, DROP, and TRUNCATE

DELETE : Removes rows : Can use WHERE

DROP : Removes table : Deletes structure

TRUNCATE : Removes all rows : Faster than DELETE

Example:

DELETE FROM users WHERE id = 1;

🧠 141. What is MongoDB?

MongoDB is a NoSQL database that stores data in JSON-like documents.

Features:

✅ Flexible schema

✅ High scalability

✅ Fast performance

Example Document:

{

"name": "Deepak",

"age": 25

}

🧠 142. Difference Between MongoDB and MySQL

MongoDB : NoSQL : Flexible schema : Document-based

MySQL : SQL : Fixed schema : Table-based

🧠 143. What is Schema?

Schema defines structure of database.

Example:

CREATE TABLE users (

id INT,

name VARCHAR(50)

);

🧠 144. What is ORM?

ORM stands for: 👉 Object Relational Mapping

ORM allows interaction with database using programming language objects.

Benefits:

✅ Easier queries

✅ Cleaner code

✅ Faster development

🧠 145. What is Sequelize?

Sequelize is an ORM for Node.js.

Example:

User.findAll();

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🧠 126. What is nodemon?

nodemon automatically restarts server after code changes.

Install:

npm install -g nodemon

🧠 127. What are Streams in Node.js?

Streams process data piece by piece instead of loading all at once.

Types:

• Readable

• Writable

• Duplex

• Transform

Benefits:

✅ Memory efficient

✅ Faster processing

🧠 128. What is Buffering?

Buffer temporarily stores binary data in memory.

Example:

const buffer = Buffer.from("Hello");

🧠 129. What is Async Middleware?

Middleware using async/await.

Example:

app.get("/", async (req, res) => {

const data = await fetchData();

res.json(data);

});

🧠 130. What is Rate Limiting?

Rate limiting restricts number of requests from users.

Benefits:

✅ Prevents abuse

✅ Protects APIs

✅ Improves security

Example:

const rateLimit = require("express-rate-limit");

Double Tap ❤️ For Part-6

🚀 Web Development Interview Questions with Answers — Part 5: Node.js

🧠 111. What is Node.js?

Node.js is a JavaScript runtime built on Chrome’s V8 engine.

It allows JavaScript to run outside the browser.

Features:

✅ Fast execution

✅ Event-driven

✅ Non-blocking I/O

✅ Scalable applications

Example:

console.log("Hello Node.js");

🧠 112. Why Use Node.js?

Advantages:

✅ Fast performance

✅ Single programming language for frontend & backend

✅ Handles multiple requests efficiently

✅ Huge npm ecosystem

Best Use Cases:

• APIs

• Real-time apps

• Chat applications

• Streaming services

🧠 113. What is npm?

npm stands for: 👉 Node Package Manager

Used to install libraries/packages.

Example:

npm install express

Uses:

• Install packages

• Manage dependencies

• Run scripts

🧠 114. Difference Between CommonJS and ES Modules

CommonJS : Uses require() : Uses module.exports

ES Modules : Uses import : Uses export

CommonJS:

const fs = require("fs");

ES Modules:

import fs from "fs";

🧠 115. What is Express.js?

Express.js is a minimal backend framework for Node.js.

Features:

✅ Routing

✅ Middleware support

✅ API development

Example:

const express = require("express");

const app = express();

app.get("/", (req, res) => {

res.send("Hello");

});

🧠 116. What is Middleware?

Middleware functions execute between: Request → Response

Uses:

• Authentication

• Logging

• Validation

Example:

app.use((req, res, next) => {

console.log("Middleware");

next();

});

🧠 117. What is REST API?

REST API follows REST architecture principles.

Common Methods:

• GET

• POST

• PUT

• DELETE

Example:

app.get("/users", (req, res) => {

res.json(users);

});

🧠 118. Difference Between PUT and PATCH

PUT : Updates entire resource

PATCH : Updates partial resource

Example:

PUT /user/1

PATCH /user/1

🧠 119. What is JWT?

JWT stands for: 👉 JSON Web Token

Used for authentication.

Structure:

Header.Payload.Signature

Benefits:

✅ Secure authentication

✅ Stateless sessions

🧠 120. What is Authentication vs Authorization?

Authentication : Verifies identity

Authorization : Verifies permissions

Example:

• Login → Authentication

• Admin access → Authorization

🧠 121. What is CORS?

CORS stands for: 👉 Cross-Origin Resource Sharing

It controls resource sharing between different domains.

Example:

app.use(cors());

🧠 122. What is dotenv?

dotenv loads environment variables from .env file.

Example:

require("dotenv").config();

.env

PORT=5000

🧠 123. What is Event Loop?

Event loop handles asynchronous operations in Node.js.

Process:

1. Executes synchronous code

2. Handles callbacks

3. Processes async tasks

Benefits:

✅ Non-blocking execution

✅ Efficient concurrency

🧠 124. What is Non-Blocking I/O?

Node.js can process multiple requests without waiting.

Benefits:

✅ Faster performance

✅ Better scalability

🧠 125. What is package.json?

package.json stores project metadata and dependencies.

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🧠 96 Difference Between Redux and Context API

Redux : Advanced state management : Better for large apps

Context API : Simple global state : Better for smaller apps

🧠 97. What are React Hooks?

Hooks allow functional components to use:

• State

• Lifecycle features

Common Hooks:

• useState

• useEffect

• useRef

• useMemo

• useCallback

🧠 98. What is useRef?

useRef stores mutable values without re-rendering.

Example:

const inputRef = useRef();

Uses:

• Access DOM elements

• Store previous values

🧠 99. What is useMemo?

useMemo optimizes expensive calculations.

Example:

const result = useMemo(() => {

return calculate(data);

}, [data]);

🧠 100. What is useCallback?

useCallback memoizes functions.

Example:

const memoFn = useCallback(() => {

console.log("Hello");

}, []);

🧠 101. What is Lazy Loading in React?

Lazy loading loads components only when needed.

Example:

const Home = React.lazy(() => import("./Home"));

Benefits:

✅ Faster loading

✅ Better performance

🧠 102. What is React Router?

React Router handles navigation in React applications.

Example:

} />

🧠 103. What are Controlled Components?

Form elements controlled by React state.

Example:

setName(e.target.value)}

/>

🧠 104. What are Uncontrolled Components?

Form elements managed by DOM itself.

Example:

🧠 105. What is Lifting State Up?

Moving shared state to common parent component.

Benefits:

✅ Better state sharing

✅ Improved synchronization

🧠 106. What is Higher Order Component HOC?

HOC is a function that takes component and returns enhanced component.

Example:

const Enhanced = withAuth(Component);

🧠 107. What are Custom Hooks?

Custom hooks reuse logic across components.

Example:

function useFetch() {

// logic

}

🧠 108. What is Strict Mode?

React Strict Mode helps identify potential issues.

Example:



🧠 109. What is Server-Side Rendering SSR?

SSR renders React components on server before sending to browser.

Benefits:

✅ Better SEO

✅ Faster initial load

🧠 110. Difference Between CSR and SSR

CSR : Rendered in browser : Slower initial load : SEO less optimized

SSR : Rendered on server : Faster initial load : Better SEO

Double Tap ❤️ For Part-5

🚀 Web Development Interview Questions with Answers — Part 4: ReactJS

🧠 81. What is React?

React is a JavaScript library used to build user interfaces.

It was developed by Meta.

Features:

✅ Component-based architecture

✅ Virtual DOM

✅ Reusable UI components

✅ Fast rendering

Example:

function App() {

return

Hello React

;

}

🧠 82. What are Components in React?

Components are reusable building blocks of UI.

Types:

• Functional Components

• Class Components

Example:

function Welcome() {

return

Welcome

;

}

🧠 83. Difference Between Functional and Class Components

Functional Component : Simpler syntax : Uses hooks : Preferred nowadays

Class Component : More complex : Uses lifecycle methods : Older approach

Functional Example:

function App() {

return

Hello

;

}

🧠 84. What is JSX?

JSX stands for: 👉 JavaScript XML

It allows writing HTML inside JavaScript.

Example:

const element =

Hello

;

Benefits:

✅ Cleaner syntax

✅ Easier UI development

🧠 85. What are Props?

Props are used to pass data between components.

Example:

function User(props) {

return

{props.name}

;

}

Usage:

🧠 86. What is State?

State stores dynamic data inside components.

Example:

const [count, setCount] = useState(0);

Uses:

• Form handling

• Counters

• Dynamic UI updates

🧠 87. Difference Between State and Props

State : Managed inside component : Mutable

Props : Passed from parent : Immutable

🧠 88. What is useState Hook?

useState manages state in functional components.

Example:

import { useState } from "react";

function Counter() {

const [count, setCount] = useState(0);

return (

setCount(count + 1)}>

{count}



);

}

🧠 89. What is useEffect Hook?

useEffect handles side effects.

Example:

useEffect(() => {

console.log("Component Loaded");

}, []);

Uses:

• API calls

• Timers

• Event listeners

🧠 90. What is Virtual DOM?

Virtual DOM is a lightweight copy of real DOM.

React updates only changed parts instead of entire page.

Benefits:

✅ Faster updates

✅ Better performance

🧠 91. What is Reconciliation?

Reconciliation is React’s process of comparing:

• Old Virtual DOM

• New Virtual DOM

Then updating only changed elements.

🧠 92. What are Keys in React?

Keys uniquely identify list items.

Example:

items.map(item => (

• {item.name}

));

Benefits:

✅ Better rendering

✅ Efficient updates

🧠 93. What is Prop Drilling?

Passing props through multiple nested components unnecessarily.

Problem:

App → Parent → Child → GrandChild

Solution:

• Context API

• Redux

🧠 94. What is Context API?

Context API shares data globally without prop drilling.

Example:

const UserContext = createContext();

Uses:

• Theme management

• Authentication

• Global settings

🧠 95. What is Redux?

Redux is a state management library used in React applications.

Concepts:

• Store

• Actions

• Reducers

Benefits:

✅ Centralized state

✅ Predictable state updates

.