Top 25 React Interview Questions and Answers for 2026 React is one of the most popular frontend libraries used by companies worldwide. If you're preparing for frontend interviews, these React interview questions will help you revise important concepts quickly. React is a JavaScript library developed by Facebook for building user interfaces using reusable components. Virtual DOM is a lightweight copy of the real DOM. React compares changes in the Virtual DOM and updates only the necessary parts in the real DOM, improving performance. Components are reusable building blocks in React that return UI elements. Functional Components Class Components JSX stands for JavaScript XML. It allows developers to write HTML-like syntax inside JavaScript. Example: function App() { return Hello React; } Props State Read-only Mutable Passed from parent Managed inside component Used for communication Used for dynamic data Hooks allow functional components to use state and lifecycle features. useState useEffect useMemo useCallback useRef useEffect is used for side effects like: API calls Timers Event listeners Example: useEffect(() => { fetchData(); }, []); State stores dynamic data inside a component and causes re-rendering when updated. Example: const [count, setCount] = useState(0); Conditional rendering means displaying UI based on conditions. Example: {isLoggedIn ? : } Keys help React identify changed items efficiently during rendering. Example: items.map(item => ( {item.name} )) React remains highly demanded because: Huge job market Strong ecosystem Used by startups and enterprises Excellent performance Preparing React interview questions regularly can improve confidence and technical understanding. You can find more React interview questions, JavaScript interview preparation, Node.js questions, and coding interview resources at: https://techqa.online react #javascript #webdev #frontend #career