Skip to main content

React Interview Questions - 2025 Edition

⚛️ React Fundamentals​

  1. What is React? React vs Angular vs Vue comparison
  2. Virtual DOM vs Real DOM - Reconciliation Process
  3. JSX - Syntax, Transpilation, and Browser Understanding
  4. React Elements vs Components
  5. Component Composition vs Inheritance
  6. Unidirectional Data Flow
  7. React Fiber Architecture
  8. React 18 Features (Concurrent Features, Automatic Batching)

🏗️ Components & Lifecycle​

  1. Class Components vs Functional Components
  2. Component Lifecycle Methods (Mounting, Updating, Unmounting)
  3. Error Boundaries & componentDidCatch
  4. Pure Components & React.memo
  5. Higher-Order Components (HOCs)
  6. Render Props Pattern
  7. Component Re-rendering & Optimization
  8. shouldComponentUpdate vs React.memo

🎣 React Hooks​

  1. useState - State Management in Functional Components
  2. useEffect - Side Effects & Lifecycle Replacement
  3. useContext - Context API with Hooks
  4. useReducer - Complex State Management
  5. useMemo - Memoization for Expensive Calculations
  6. useCallback - Function Memoization
  7. useRef - DOM References & Mutable Values
  8. useImperativeHandle - Exposing Component APIs
  9. useLayoutEffect vs useEffect
  10. Custom Hooks - Reusable Logic
  11. Hook Rules & ESLint Plugin
  12. React 18 Hooks (useId, useDeferredValue, useTransition)

📊 State Management​

  1. Local State vs Global State
  2. Props vs State
  3. Lifting State Up
  4. State Colocation
  5. Context API - Provider & Consumer
  6. Context Performance Optimization
  7. useState vs useReducer - When to Use Which
  8. State Normalization

🔄 Redux & State Libraries​

  1. Redux Core Concepts (Store, Actions, Reducers)
  2. Redux Data Flow
  3. Redux Middleware (Thunk, Saga)
  4. Redux Toolkit (RTK) - Modern Redux
  5. useSelector & useDispatch Hooks
  6. Redux vs Context API
  7. Zustand, Jotai, Valtio - Modern State Libraries
  8. Server State vs Client State
  9. React Query/TanStack Query
  10. SWR for Data Fetching

🎨 Rendering & Performance​

  1. React Rendering Process
  2. Reconciliation Algorithm
  3. Keys in React Lists
  4. Code Splitting with React.lazy & Suspense
  5. Dynamic Imports
  6. Bundle Splitting Strategies
  7. Tree Shaking
  8. React DevTools Profiler
  9. Performance Optimization Techniques
  10. Concurrent Features (useTransition, useDeferredValue)

📝 Forms & Events​

  1. Controlled vs Uncontrolled Components
  2. Form Handling Best Practices
  3. Form Libraries (Formik, React Hook Form)
  4. Synthetic Events
  5. Event Handling & Event Delegation
  6. Form Validation Strategies
  7. File Upload Handling

🌐 Data Fetching & APIs​

  1. Fetch API in React
  2. Async/Await in useEffect
  3. Error Handling in Data Fetching
  4. Loading States Management
  5. Caching Strategies
  6. Optimistic Updates
  7. Polling & Real-time Data
  8. GraphQL with React (Apollo, Relay)

🎭 Advanced Patterns​

  1. Compound Components Pattern
  2. Render Props Pattern
  3. Provider Pattern
  4. Container/Presentational Pattern
  5. Hooks Pattern
  6. State Reducer Pattern
  7. Control Props Pattern
  8. Custom Hook Patterns

🖥️ Rendering Patterns​

  1. Client-Side Rendering (CSR)
  2. Server-Side Rendering (SSR)
  3. Static Site Generation (SSG)
  4. Incremental Static Regeneration (ISR)
  5. React Server Components (RSC)
  6. Streaming SSR
  7. Progressive Hydration
  8. Selective Hydration
  9. Islands Architecture

🔧 Testing​

  1. Unit Testing with Jest & React Testing Library
  2. Component Testing Strategies
  3. Mocking in Tests
  4. Integration Testing
  5. E2E Testing with Cypress/Playwright
  6. Snapshot Testing
  7. Testing Custom Hooks
  8. Testing Async Components

♿ Accessibility & SEO​

  1. React Accessibility Best Practices
  2. ARIA Attributes in JSX
  3. Keyboard Navigation
  4. Screen Reader Support
  5. Focus Management
  6. SEO in React Applications
  7. Meta Tags & Helmet

🔒 Security​

  1. XSS Prevention in React
  2. Sanitizing User Input
  3. Secure API Communication
  4. Authentication Patterns
  5. JWT Handling
  6. CSRF Protection

🛠️ Development Tools​

  1. React DevTools
  2. Hot Reloading & Fast Refresh
  3. ESLint Rules for React
  4. Prettier Configuration
  5. TypeScript with React
  6. Webpack Configuration
  7. Vite for React Development

💻 Machine Coding Challenges​

🎯 Essential Components​

  1. Counter App with Increment/Decrement
  2. Todo List with CRUD Operations
  3. Accordion/Collapsible Component
  4. Tabs Component
  5. Modal/Dialog Component
  6. Dropdown/Select Component
  7. Pagination Component
  8. Star Rating Component
  9. Progress Bar Component

🎮 Interactive Components​

  1. Tic Tac Toe Game
  2. Memory Card Game
  3. Snake Game
  4. Calculator
  5. Stopwatch/Timer
  6. Countdown Timer
  7. Traffic Light Simulator

📊 Data Display Components​

  1. Data Table with Sorting/Filtering
  2. Infinite Scrolling List
  3. Virtual Scrolling
  4. Image Carousel/Slider
  5. Image Gallery with Lightbox
  6. Chart Components (Bar, Line, Pie)
  7. Calendar/Date Picker

🔍 Search & Filter Components​

  1. Typeahead/Autocomplete
  2. Search with Debouncing
  3. Multi-select Dropdown
  4. Filter/Sort Interface
  5. Tag Input Component

📱 Advanced UI Components​

  1. Drag & Drop Interface
  2. Resizable Panels
  3. File Upload with Preview
  4. Rich Text Editor
  5. Code Editor Component
  6. Nested Menu/Tree View
  7. Transfer List Component
  8. Kanban Board

🎨 Layout Components​

  1. Responsive Grid System
  2. Masonry Layout
  3. Split Pane Component
  4. Sidebar Navigation
  5. Breadcrumb Component

🔧 Custom Hooks​

  1. useLocalStorage Hook
  2. useFetch/useAPI Hook
  3. useDebounce Hook
  4. useClickOutside Hook
  5. useIntersectionObserver Hook
  6. useWindowSize Hook
  7. usePrevious Hook
  8. useToggle Hook

🏗️ Architecture Challenges​

  1. Shopping Cart Application
  2. Chat Application
  3. Dashboard with Widgets
  4. Form Builder
  5. Multi-step Form Wizard
  6. Real-time Collaboration Tool
  7. Social Media Feed

🌟 2025 Trending Topics​

  1. React Server Components Deep Dive
  2. Concurrent Rendering & Suspense
  3. React 19 Features
  4. Micro-frontends with React
  5. React Native for Web
  6. WebAssembly with React
  7. AI/ML Integration in React Apps
  8. Edge Computing & React

📚 Essential Resources​