Web Development

🧠 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 ----- 1.31 ₽ · /balance_help

🚀 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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Example: { "name": "myapp", "version": "1.0.0" } 🧠 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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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 **🧠 96.

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**Difference Between Synchronous and Asynchronous Programming Synchronous** : Executes line by line Blocking  Asynchronous : Executes independently Non-blocking  Example: setTimeout(() => {    console.log("Hello"); }, 2000); 🧠 61. What is Promise in JavaScript? Promise handles asynchronous operations.  States:  • Pending  • Resolved  • Rejected  Example: const promise = new Promise((resolve, reject) => {    resolve("Success"); }); 🧠 62. What are async and await? Used to simplify asynchronous code.  Example: async function getData() {    const response = await fetch(url); } 🧠 63. What is setTimeout? Runs code after specific delay.  Example: setTimeout(() => {    console.log("Hello"); }, 3000); 🧠 64. Difference Between map(), filter(), and reduce() Method : Purpose map() : Transform array filter() : Filter array reduce() : Reduce array to single value  Example: const nums = [1,2,3];  nums.map(n => n * 2); 🧠 65. What is Destructuring? Extract values from arrays or objects.  Example: const person = {    name: "Deepak" };  const { name } = person; 🧠 66. What is Spread Operator? Spread operator expands elements.  Example: const arr1 = [1,2]; const arr2 = [...arr1, 3]; 🧠 67. What is Rest Operator? Collects multiple values into array.  Example: function sum(...nums) {    console.log(nums); } 🧠 68. What is Template Literal? Template literals allow embedded expressions.  Example: let name = "Narayan";  console.log(Hello ${name}); 🧠 69. What is Optional Chaining? Safely accesses nested properties.  Example: user?.address?.city 🧠 70. Explain this Keyword this refers to current object.  Example: const user = {    name: "Radhe",    greet() {       console.log(this.name);    } }; 🧠 71. Difference Between Function Declaration and Function Expression Declaration : Hoisted  Expression : Not fully hoisted  Example: function test() {}  const demo = function() {}; 🧠 72. What is Prototype? Prototype allows inheritance in JavaScript.  Example: function Person() {}  Person.prototype.age = 25; 🧠 73. What is Prototypal Inheritance? Objects inherit properties from other objects.  Example: child.proto = parent; 🧠 74. What is JSON? JSON stands for: 👉 JavaScript Object Notation  Used for data exchange.  Example: {    "name": "Sanyam",    "age": 26 } 🧠 75. Difference Between localStorage and sessionStorage localStorage : Permanent Shared across tabs  sessionStorage : Temporary Limited to tab 🧠 76. What is NaN? NaN means: 👉 Not a Number  Example: console.log("abc" / 2); 🧠 77. What are Truthy and Falsy Values? Falsy Values:  • false  • 0  • ""  • null  • undefined  • NaN  Everything else is truthy. 🧠 78. What is Debounce? Debounce limits repeated function calls.  Used in:  • Search bars  • Resize events  Example: function debounce(fn, delay) {} 🧠 79. What is Throttle? Throttle limits execution rate.  Example: function throttle(fn, limit) {} **🧠 80. What is Currying?** Currying converts function with multiple arguments into nested functions.  Example: function add(a) {    return function(b) {       return a + b;    }; } Double Tap ❤️ For Part-4

🚀 Web Development Interview Questions with Answers — Part 3: JavaScript 🧠 46. What is JavaScript? JavaScript is a programming language used to make web pages interactive. It is used for: • Form validation • Dynamic content • API calls • Animations • Interactive UI Example: console.log("Hello World"); 🧠 47. Difference Between var, let, and const var : Function scoped Can redeclare Can reassign let : Block scoped Cannot redeclare Can reassign const : Block scoped Cannot redeclare Cannot reassign Example: var a = 10; let b = 20; const c = 30; 🧠 48. What are Data Types in JavaScript? Primitive Data Types: • String • Number • Boolean • Null • Undefined • Symbol • BigInt Non-Primitive: • Object • Array • Function Example: let name = "Sanyam"; let age = 26; let isActive = true; 🧠 49. Difference Between null and undefined null : Intentional empty value undefined : Variable declared but not assigned Example: let a = null; let b; console.log(b); 🧠 50. What is Hoisting? Hoisting means JavaScript moves declarations to the top before execution. Example: console.log(a); var a = 10; Output: undefined 🧠 51. Explain Scope in JavaScript Scope determines where variables are accessible. Types: • Global Scope • Function Scope • Block Scope Example: { let age = 26; } age cannot be accessed outside block. 🧠 52. What is Closure? A closure allows a function to access variables from its outer function even after execution. Example: function outer() { let count = 0; return function inner() { count++; console.log(count); }; } const fn = outer(); fn(); 🧠 53. What is Callback Function? A callback is a function passed into another function. Example: function greet(name, callback) { console.log(name); callback(); } greet("Deepak", function() { console.log("Welcome"); }); 🧠 54. What is Arrow Function? Arrow functions provide shorter syntax. Example: const add = (a, b) => a + b; Benefits: ✅ Cleaner syntax ✅ Lexical this 🧠 55. Difference Between == and === == : Checks value only === : Checks value and type Example: 5 == "5" // true 5 === "5" // false 🧠 56. What is Event Bubbling? Event bubbling means events move from child to parent. Example: button.addEventListener("click", () => { console.log("Button clicked"); }); 🧠 57. What is Event Capturing? Event capturing is opposite of bubbling. Event moves: Parent → Child Example: element.addEventListener("click", fn, true); 🧠 58. What is Event Delegation? Using parent element to handle child events. Benefits: ✅ Better performance ✅ Dynamic elements support Example: parent.addEventListener("click", (e) => { console.log(e.target); }); 🧠 59. What is DOM? DOM stands for: 👉 Document Object Model It represents HTML as objects. Example: document.getElementById("title"); **🧠 60.

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🧠 37. What are CSS Transitions?  Transitions create smooth changes between property values.  Example:

button {
   transition: background 0.3s ease;
}

🧠 38. Difference Between Transition and Animation  Transition : Triggered by event  Simple effects  Animation : Can run automatically  Complex effects  Example:

@keyframes move {
   from { left:0; }
   to { left:100px; }
}

🧠 39. What is transform Property?  transform changes element shape or position.  Example:

div {
   transform: rotate(45deg);
}

Common Functions:  - rotate()  - scale()  - translate()  🧠 40. What is overflow Property?  Controls content overflow behavior.  Values:  - visible  - hidden  - scroll  - auto  Example:

div {
   overflow: scroll;
}

🧠 41. Explain CSS Inheritance  Some CSS properties automatically pass from parent to child.  Example:

body {
   color: blue;
}

Child elements inherit text color.  🧠 42. What is !important?  !important gives highest priority to a CSS rule.  Example:

p {
   color: red !important;
}

🧠 43. What are CSS Preprocessors?  Preprocessors extend CSS functionality.  Popular Preprocessors:  - SASS  - SCSS  - LESS  Features:  ✅ Variables  ✅ Nesting  ✅ Functions  🧠 44. Difference Between SCSS and SASS  SCSS : Uses braces  CSS-like syntax  SASS : No braces  Indentation syntax  SCSS Example:

$color: blue;

h1 {
   color: $color;
}

🧠 45. What is Bootstrap?  Bootstrap is a popular CSS framework used for responsive web development.  Features:  ✅ Responsive grid system  ✅ Prebuilt components  ✅ Faster development  Example:

<button class="btn btn-primary">
   Click Me
</button>

Double Tap ❤️ For Part-3

Sure! Here’s the revised content with ** replacing *: --- 🚀 Web Development Interview Questions with Answers — Part 2: CSS 🧠 21. What is CSS? CSS stands for Cascading Style Sheets. It is used to style and design HTML elements. CSS helps to: • Add colors • Set fonts • Create layouts • Add animations • Make websites responsive Example:

h1 {
   color: blue;
   font-size: 40px;
}

🧠 22. Difference Between Inline, Internal, and External CSS Type : Description Inline CSS : Written inside HTML element Internal CSS : Written inside <style> tag External CSS : Written in separate .css file Inline CSS:

<h1 style="color:red;">Hello</h1>

Internal CSS:

<style>
h1 {
   color: blue;
}
</style>

External CSS:

<link rel="stylesheet" href="style.css">

🧠 23. What is Specificity in CSS? Specificity determines which CSS rule is applied when multiple rules target the same element. Priority Order: 1. Inline CSS 2. ID Selector 3. Class Selector 4. Element Selector Example:

#title {
   color: red;
}

.heading {
   color: blue;
}

ID selector has higher priority. 🧠 24. Explain CSS Box Model Every HTML element is treated as a box. The box model contains: • Content • Padding • Border • Margin Structure:

Margin
 └ Border
    └ Padding
       └ Content

Example:

div {
   padding: 20px;
   border: 2px solid black;
   margin: 10px;
}

🧠 25. Difference Between Margin and Padding Margin : Space outside border Creates gap between elements Padding : Space inside border Creates inner spacing Example:

div {
   margin: 20px;
   padding: 20px;
}

🧠 26. What is Flexbox? Flexbox is a one-dimensional layout system used for alignment and spacing. Benefits: ✅ Easy alignment ✅ Responsive layouts ✅ Flexible spacing Example:

.container {
   display: flex;
   justify-content: center;
   align-items: center;
}

🧠 27. What is CSS Grid? CSS Grid is a two-dimensional layout system. It handles: • Rows • Columns Example:

.container {
   display: grid;
   grid-template-columns: 1fr 1fr;
}

🧠 28. Difference Between Relative, Absolute, Fixed, and Sticky Positioning Position : Description relative : Positioned relative to itself absolute : Positioned relative to parent fixed : Fixed on screen sticky : Sticks during scrolling Example:

div {
   position: absolute;
   top: 20px;
}

🧠 29. What is z-index? z-index controls stack order of elements. Higher z-index appears on top. Example:

.box {
   z-index: 10;
}

🧠 30. Difference Between em, rem, %, px, vh, and vw Unit : Meaning px : Fixed pixels % : Relative percentage em : Relative to parent rem : Relative to root vh : Viewport height vw : Viewport width Example:

h1 {
   font-size: 2rem;
}

🧠 31. What are Pseudo-Classes? Pseudo-classes define special states of elements. Examples:

a:hover {
   color: red;
}

Common Pseudo-Classes: • :hover • :focus • :first-child • :last-child 🧠 32. What are Pseudo-Elements? Pseudo-elements style specific parts of elements. Example:

p::first-letter {
   font-size: 40px;
}

Common Pseudo-Elements: • ::before • ::after • ::first-letter 🧠 33. Difference Between visibility:hidden and display:none visibility:hidden : Element hidden but space remains display:none : Element removed completely Example:

.box {
   display: none;
}

🧠 34. What is Media Query? Media queries make websites responsive. Example:

@media (max-width: 768px) {
   body {
      background: lightblue;
   }
}

🧠 35. Explain Responsive Design Responsive design ensures websites work on: • Mobile • Tablet • Desktop Techniques: ✅ Media Queries ✅ Flexible layouts