React.js and Next.js have rapidly become the cornerstone technologies for building powerful, scalable, and user-friendly web applications. As companies increasingly demand modern full-stack skills, proficiency in React and Next.js is becoming a must-have for frontend and full-stack developers alike.<\/p>\n\n\n\n
In this guide, we’ve carefully compiled the top 50 React.js and Next.js interview questions and answers<\/strong> that hiring managers are actively asking in 2026. Whether you’re a fresher stepping into your first React job<\/strong><\/a> or an experienced engineer aiming for a senior developer position, this resource will equip you with the essential knowledge to succeed.<\/p>\n\n\n\n Let’s dive deep and master the core concepts and real-world practicalities of React and Next.js!<\/p>\n\n\n\n Related Read: Coding and Programming Interview Questions <\/a>[ 2026 ]<\/a><\/strong><\/p>\n\n\n\n Related Read: <\/a>Top 10 Programming Languages to Learn in 2026<\/a><\/strong><\/p>\n\n\n\n Related Read: 100+ Node.js Interview Questions and Answers [ 2026 ]<\/a><\/strong><\/p>\n\n\n\n Related Read: 100+ JavaScript Interview Questions and Answers<\/a> [ 2026 ]<\/a><\/strong><\/p>\n\n\n\n Related Read: Front End Developer Interview Questions and Answers [ 2026 ]<\/a><\/strong><\/p>\n\n\n\n Related Read: JavaScript ES6+ Features You Must Know for Interviews in [ 2026 ]<\/a><\/strong><\/p>\n\n\n\n Related Read: HTML and CSS Interview Questions & Answers [ 2026 ]<\/a><\/strong><\/p>\n\n\n\n Related Read: Full Stack Developer Skills You Can Add to Your Resume<\/a><\/strong><\/p>\n\n\n\n If you\u2019re preparing for a React.js or Next.js interview in 2026, you\u2019re already investing in two of the most in-demand and future-proof skills in tech. Frontend and full-stack development are evolving fast, and companies aren\u2019t just hiring coders anymore. They\u2019re looking for engineers who understand architecture, performance, and user experience.<\/p>\n\n\n\n Mastering the core concepts of React.js<\/strong> and Next.js<\/strong> will give you an edge that many candidates still lack. And it\u2019s not just about knowing the syntax \u2014 it’s about knowing when, where, and why to use these technologies.<\/p>\n\n\n\n Our advice? Go beyond theory. Build small projects. Debug stubborn bugs. Get your hands dirty with server-side rendering, dynamic routes, and performance tuning. Interviews today often mirror the real-world challenges developers face, and showing practical thinking can set you apart.<\/p>\n\n\n\n We hope these Next JS and React JS interview questions<\/a><\/strong> help you think deeper, answer smarter, and ultimately land the opportunity you\u2019re aiming for.<\/p>\n\n\n\nTable of Contents<\/h2>\n
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React.js Basic Interview Questions<\/h2>\n\n\n\n
1. What is React.js?<\/h3>\n\n\n\n
2. What are the main features of React?<\/h3>\n\n\n\n
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3. What is JSX?<\/h3>\n\n\n\n
4. What are components in React?<\/h3>\n\n\n\n
5. What is the difference between Functional and Class components?<\/h3>\n\n\n\n
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React.Component<\/code> and can manage state and lifecycle using methods.<\/li>\n<\/ul>\n<\/div>\n\n\n\n6. What is the Virtual DOM in React?<\/h3>\n\n\n\n
7. What are props in React?<\/h3>\n\n\n\n
8. What is state in React?<\/h3>\n\n\n\n
9. What is the difference between state and props?<\/h3>\n\n\n\n
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10. What are lifecycle methods in React?<\/h3>\n\n\n\n
componentDidMount()<\/code>, shouldComponentUpdate()<\/code>, and componentWillUnmount()<\/code>.<\/div>\n\n\n\n11. What is useState Hook?<\/h3>\n\n\n\n
useState<\/code> is a React Hook that allows functional components to maintain internal state without converting them to class components.<\/div>\n\n\n\n12. What is useEffect Hook?<\/h3>\n\n\n\n
useEffect<\/code> lets you perform side effects (data fetching, DOM manipulation, etc.) inside functional components. It replaces lifecycle methods like componentDidMount<\/code> and componentDidUpdate<\/code>.<\/div>\n\n\n\n13. What is lifting state up in React?<\/h3>\n\n\n\n
14. What is React Router?<\/h3>\n\n\n\n
15. What is conditional rendering in React?<\/h3>\n\n\n\n
if<\/code>, ternary<\/code>, or logical operators.<\/div>\n\n\n\n\nReact.js Intermediate Interview Questions<\/h2>\n\n\n\n
16. What is the Context API in React?<\/h3>\n\n\n\n
React.createContext()<\/code> and accessed using the Provider<\/code> and useContext<\/code> hook.<\/div>\n\n\n\n17. What is useContext Hook in React?<\/h3>\n\n\n\n
useContext<\/code> is a Hook that simplifies accessing data from a Context provider. It avoids the need to wrap components manually and allows direct consumption of context values inside functional components.<\/div>\n\n\n\n18. What is useReducer Hook in React?<\/h3>\n\n\n\n
useReducer<\/code> is a React Hook used for managing complex state logic by dispatching actions. It\u2019s ideal when the next state depends heavily on the previous state or when dealing with multiple sub-values in a state object.<\/div>\n\n\n\n19. What is the difference between useState and useReducer?<\/h3>\n\n\n\n
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20. What are controlled and uncontrolled components in React?<\/h3>\n\n\n\n
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21. What is the useRef Hook in React?<\/h3>\n\n\n\n
useRef<\/code> returns a mutable ref object whose .current<\/code> property persists for the full lifetime of the component. It\u2019s commonly used for accessing DOM nodes or storing persistent values across renders without causing re-renders.<\/div>\n\n\n\n22. What is memoization in React?<\/h3>\n\n\n\n
React.memo()<\/code>, useMemo()<\/code>, and useCallback()<\/code> provide memoization.<\/div>\n\n\n\n23. How does React.memo work?<\/h3>\n\n\n\n
React.memo<\/code> is a higher-order component that prevents re-rendering if props haven’t changed. It\u2019s used to optimize performance for functional components by memoizing the rendered output.<\/div>\n\n\n\n24. What is useCallback Hook?<\/h3>\n\n\n\n
useCallback<\/code> returns a memoized version of the callback function that only changes if one of its dependencies changes. It’s useful when passing callbacks to optimized child components.<\/div>\n\n\n\n25. What is useMemo Hook?<\/h3>\n\n\n\n
useMemo<\/code> returns a memoized value. It recomputes the value only when dependencies change, preventing unnecessary expensive calculations on every render.<\/div>\n\n\n\n\n26. What is code splitting in React?<\/h3>\n\n\n\n
import()<\/code> and libraries like React.lazy and Loadable Components.<\/div>\n\n\n\n27. What is React.lazy and Suspense?<\/h3>\n\n\n\n
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28. How can you optimize the performance of a React application?<\/h3>\n\n\n\n
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29. What is error boundary in React?<\/h3>\n\n\n\n
componentDidCatch<\/code> and getDerivedStateFromError<\/code>.<\/div>\n\n\n\n30. What is a Higher-Order Component (HOC) in React?<\/h3>\n\n\n\n
Next.js Fundamentals Interview Questions<\/h2>\n\n\n\n
31. What is Next.js?<\/h3>\n\n\n\n
32. What are the main features of Next.js?<\/h3>\n\n\n\n
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33. What is the difference between SSR and SSG in Next.js?<\/h3>\n\n\n\n
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34. What is getStaticProps in Next.js?<\/h3>\n\n\n\n
getStaticProps<\/code> is an async function used in Next.js pages to fetch data at build time. It enables static site generation with dynamic data.<\/div>\n\n\n\n\n35. What is getServerSideProps in Next.js?<\/h3>\n\n\n\n
getServerSideProps<\/code> is an async function used to fetch data on every request. It enables server-side rendering where fresh data is needed at runtime.<\/div>\n\n\n\n36. What is getStaticPaths in Next.js?<\/h3>\n\n\n\n
getStaticPaths<\/code> works with getStaticProps<\/code> to generate dynamic routes during the build process. It defines a list of paths that need to be statically generated.<\/div>\n\n\n\n37. How does file-based routing work in Next.js?<\/h3>\n\n\n\n
\/pages<\/code> directory automatically maps to corresponding routes in the application.<\/div>\n\n\n\n38. How do you create dynamic routes in Next.js?<\/h3>\n\n\n\n
\/pages<\/code> directory, such as [id].js<\/code>, to capture dynamic segments in the URL.<\/div>\n\n\n\n39. What are API Routes in Next.js?<\/h3>\n\n\n\n
\/pages\/api<\/code> directory without needing a separate server.<\/div>\n\n\n\n40. How do you perform image optimisation in Next.js?<\/h3>\n\n\n\n
next\/image<\/code> component that automatically optimizes images on-demand for faster load times and better performance, including resizing, lazy loading, and serving in modern formats like WebP.<\/div>\n\n\n\n\nConclusion<\/h2>\n\n\n\n