2026

React Interview Questions 2026

A current, 2026 snapshot of the React interview questions worth knowing — kept up to date as frameworks and best practices evolve, so you prepare with what companies are actually asking in 2026.

98Questions10Beginner31Intermediate57Senior

98 React questions

  1. 1What is React?Beginner
  2. 2What are refs used for in ReactBeginner
  3. 3What is Context API in ReactJSIntermediate
  4. 4React Interview Question 3 (Free)Senior
  5. 5React Interview Question 2 (Free)Intermediate
  6. 6How does React work?Beginner
  7. 7What is state in React?Beginner
  8. 8Explain Suspense in ReactSenior
  9. 9Implement infinite scrollingIntermediate
  10. 10Explain memoizationIntermediate
  11. 11How would you optimize a slow React app?Senior
  12. 12What causes unnecessary re-renders?Senior
  13. 13What is React Fiber?Senior
  14. 14How do keys work in React?Intermediate
  15. 15Memory leaks in frontendSenior
  16. 16Explain batching in ReactSenior
  17. 17Explain React reconciliationSenior
  18. 18Explain useEffect dependency issuesSenior
  19. 19What is React component composition vs inheritance?Intermediate
  20. 20What is React render thrashing?Senior
  21. 21What is React derived state and why should it be avoided?Senior
  22. 22What is React immutable state and why is it important?Intermediate
  23. 23What is React rendering waterfall problem?Senior
  24. 24What is React suspense boundary and why is it important?Senior
  25. 25How does React prevent memory leaks?Senior
  26. 26What are React hooks lifecycle equivalents?Intermediate
  27. 27What is the difference between synchronous and concurrent rendering in React?Senior
  28. 28How does React handle state updates under the hood?Senior
  29. 29What is React commit phase?Senior
  30. 30What is React lazy boundary?Senior
  31. 31What is React higher-order component (HOC)?Intermediate
  32. 32What is React compound components pattern?Senior
  33. 33What is React render props pattern?Intermediate
  34. 34What is React tearing?Senior
  35. 35What is React incremental rendering?Senior
  36. 36What is React server-side rendering (SSR)?Intermediate
  37. 37What is React event pooling?Intermediate
  38. 38What is React selective hydration?Senior
  39. 39What is React offscreen rendering?Senior
  40. 40What is React reconciliation key collision issue?Intermediate
  41. 41What is React flushSync?Senior
  42. 42What is React hydration mismatch and how do you fix it?Senior
  43. 43How does React handle priority updates internally?Senior
  44. 44What is React streaming SSR?Senior
  45. 45What is React scheduler?Senior
  46. 46What is React controlled rendering?Senior
  47. 47What is SyntheticEvent in React?Intermediate
  48. 48What is React event delegation?Intermediate
  49. 49What is React lazy hydration?Senior
  50. 50What is React key reconciliation problem?Intermediate
  51. 51What is memoization in React?Intermediate
  52. 52What is React Context performance issue?Senior
  53. 53What is the difference between state and props?Beginner
  54. 54What is useRef and when should you use it?Intermediate
  55. 55What is React batching and how does it work in React 18?Intermediate
  56. 56What is stale closure in React and how do you fix it?Senior
  57. 57What is the difference between useLayoutEffect and useEffect?Senior
  58. 58What is React reconciliation algorithm?Senior
  59. 59What is lazy loading in React?Beginner
  60. 60What is code splitting in React?Intermediate
  61. 61What is React Profiler?Intermediate
  62. 62What is React Portals?Intermediate
  63. 63What is batching in React?Intermediate
  64. 64What causes unnecessary re-renders in React?Intermediate
  65. 65What is hydration in React?Senior
  66. 66What is React Strict Mode?Intermediate
  67. 67What is useDeferredValue?Senior
  68. 68What is useTransition and when should you use it?Senior
  69. 69What is Suspense in React?Senior
  70. 70What is React Concurrent Mode (Concurrent Rendering)?Senior
  71. 71What is React Fiber and why was it introduced?Senior
  72. 72How do error boundaries work in React and what errors do they not catch?Intermediate
  73. 73What is React context and when should you use it instead of prop drilling?Intermediate
  74. 74Explain React Server Components at a high level and how they differ from client components.Senior
  75. 75What is the purpose of keys in React lists and what makes a good key?Beginner
  76. 76How does React.memo, useMemo, and useCallback affect performance?Senior
  77. 77What is useEffect used for and how do you avoid common pitfalls with dependency arrays?Intermediate
  78. 78What are React hooks and what rules must you follow when using them?Intermediate
  79. 79Explain the difference between controlled and uncontrolled inputs in React forms.Beginner
  80. 80What is the virtual DOM in React and why does React use it?Intermediate
  81. 81React Advanced Interview Question 8Intermediate
  82. 82React Advanced Interview Question 6Senior
  83. 83What is JSX in React?Beginner
  84. 84What are React components?Beginner
  85. 85React Advanced Interview Question 9Senior
  86. 86How does React handle state batching in React 18?Senior
  87. 87Explain React concurrent renderingSenior
  88. 88How does React scheduling work internally?Senior
  89. 89How would you debug a performance bottleneck in React?Senior
  90. 90Explain useTransition and when to use itSenior
  91. 91How does React Suspense work under the hood?Senior
  92. 92Design a large-scale component architectureSenior
  93. 93What are rendering phases in React?Senior
  94. 94How would you implement a custom hook library?Senior
  95. 95Explain reconciliation edge casesSenior
  96. 96How to prevent cascading re-renders?Senior
  97. 97How to optimize large forms in React?Senior
  98. 98How would you design a design system in React?Senior

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Are these React interview questions up to date for 2026?

Yes. This page reflects 98 React interview questions kept current with today's frameworks, tooling and interview trends, with each answer maintained and dated.

What React topics should I focus on in 2026?

Prioritise the fundamentals plus the modern patterns interviewers ask about now. Each question here includes a detailed answer, code example and common mistakes so you can target the highest-impact areas.

Are these questions free?

You can read the question and a short answer for free. A subscription unlocks the full detailed explanation, real-world example, common mistakes and follow-up questions for each one.