40 React
Interview
Questions

The most frequently asked React questions in 2026 interviews — hooks, state, performance, patterns, and system design. Curated from real interviews at top companies.

"React interviews don't test if you've used it — they test if you understand it. Know your hooks, know your rendering model, know your patterns."

— The Boring Education Team

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2026

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React Hooks, State & Performance

useState useEffect useCallback useMemo useRef useContext useReducer useLayoutEffect useImperativeHandle Custom Hooks Virtual DOM Reconciliation Error Boundaries Code Splitting React.memo

01. What is React and how does it differ from Angular or Vue.js?

02. Explain the Virtual DOM and how it improves performance.

03. What are React hooks? Name commonly used hooks and their purpose.

04. Explain useEffect with a real-world example use case.

05. What is the difference between useMemo and useCallback? When do you use each?

06. How do you create and use custom hooks? Provide an example.

07. Explain reconciliation in React and how it impacts rendering.

08. What are error boundaries and how do you implement one?

09. How does useReducer differ from useState? When is it preferable?

10. What is the Context API? When would you use it vs. Redux?

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40 ReactInterviewQuestions

React Hooks, State & Performance

40 React
Interview
Questions