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React Interview Questions
140+ most important React interview questions on component architecture, hooks, state management, performance, and real-world UI components.
Questions and solutions by ex-interviewers
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Number of questions
5
0
50
questions
Total time
5
5
hours total
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React Interview Playbook
A comprehensive React interview guide that covers core concepts and interview-specific React tips
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/12 guides
GUIDES
What is React? Describe the benefits of React
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React
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What is the difference between React Node, React Element, and a React Component?
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What is JSX and how does it work?
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1.64k done
What is the difference between state and props in React?
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3.14k done
What is the purpose of the `key` prop in React?
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1.94k done
What is the consequence of using array indices as the value for `key`s in React?
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1.54k done
What is the difference between controlled and uncontrolled React Components?
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1.33k done
What are some pitfalls about using context in React?
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1.34k done
What are the benefits of using hooks in React?
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1.55k done
What are the rules of React hooks?
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1.51k done
What is the difference between `useEffect` and `useLayoutEffect` in React?
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1.15k done
What is the purpose of callback function argument format of `setState()` in React and when should it be used?
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973 done
What does the dependency array of `useEffect` affect?
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1.18k done
What is the `useRef` hook in React and when should it be used?
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1.15k done
What is the `useCallback` hook in React and when should it be used?
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1.11k done
What is the `useMemo` hook in React and when should it be used?
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1.08k done
What is the `useReducer` hook in React and when should it be used?
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969 done
What is the `useId` hook in React and when should it be used?
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867 done
What does re-rendering mean in React?
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1.11k done
What are React Fragments used for?
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1.09k done
What is `forwardRef()` in React used for?
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769 done
How do you reset a component's state in React?
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1.01k done
Why does React recommend against mutating state?
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788 done
What are error boundaries in React for?
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725 done
How do you test React applications?
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Explain what React hydration is
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724 done
What are React Portals used for?
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708 done
How do you debug React applications?
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648 done
What is React strict mode and what are its benefits?
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799 done
How do you localize React applications?
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Internationalization
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672 done
What is code splitting in a React application?
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762 done
How would one optimize the performance of React contexts to reduce rerenders?
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Performance
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945 done
What are higher order components in React?
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821 done
What is the Flux pattern and what are its benefits?
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642 done
Explain one-way data flow of React and its benefits
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873 done
How do you handle asynchronous data loading in React applications?
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Async
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1.04k done
Explain server-side rendering of React applications and its benefits?
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730 done
Explain static generation of React applications and its benefits?
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591 done
Explain the presentational vs container component pattern in React
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685 done
What are some common pitfalls when doing data fetching in React?
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664 done
What are render props in React and what are they for?
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586 done
What are some React anti-patterns?
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696 done
How do you decide between using React state, context, and external state managers?
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928 done
Explain the composition pattern in React
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679 done
What is virtual DOM in React?
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1.13k done
How does virtual DOM in React work? What are its benefits and downsides?
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1.03k done
What is React Fiber and how is it an improvement over the previous approach?
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709 done
What is reconciliation in React?
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1.05k done
What is React Suspense and what does it enable?
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681 done
Explain what happens when the `useState` setter function is called in React
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777 done