⚛️ React – Interview Prep Topics

This section provides a complete guide to React interview topics. Learn about JSX, functional vs class components, hooks like useState and useEffect, Virtual DOM, reconciliation, error boundaries, memoization, and forwardRef. Each topic includes MCQs, code examples, and real interview Q&A to ensure complete readiness.

• 1. What is React and how does it work?
• 2. Explain the virtual DOM in React.
• 3. What are the main features of React?
• 4. What is JSX and why is it used in React?
• 5. How does React differ from Angular and Vue?
• 6. What are components in React?
• 7. What is the difference between functional and class components?
• 8. What is the purpose of React hooks?
• 9. How does useState work in React?
• 10. Explain the useEffect hook with examples.
• 11. What is the difference between useEffect and componentDidMount?
• 12. What are props in React and how are they used?
• 13. How do you manage state in React?
• 14. What is lifting state up in React?
• 15. How does context API help in prop drilling?
• 16. What is Redux and how does it relate to React?
• 17. Explain the flow of data in React-Redux.
• 18. What is a reducer in Redux?
• 19. How does the useReducer hook work?
• 20. What is the difference between Redux and Context API?
• 21. How do you optimize performance in React apps?
• 22. What are React keys and why are they important?
• 23. What is reconciliation in React?
• 24. What are controlled and uncontrolled components?
• 25. How do you handle forms in React?
• 26. What is the purpose of useRef in React?
• 27. How can you create a custom hook in React?
• 28. What is memoization in React and when should you use React.memo?
• 29. What is the difference between useMemo and useCallback?
• 30. What is lazy loading in React?
• 31. How do you implement code splitting in React?
• 32. What is React Router and how do you use it?
• 33. How do you pass parameters with React Router?
• 34. What are route guards in React?
• 35. How do you handle 404 errors in React routing?
• 36. How does React handle conditional rendering?
• 37. What is the role of keys in a list rendering scenario?
• 38. What is the difference between class-based lifecycle methods and useEffect?
• 39. How does the diffing algorithm work in React?