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.
1. What is React?
React is a JavaScript library developed by Facebook for building user interfaces using reusable components.
2. What is Virtual DOM?
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.
3. What are React Components?
Components are reusable building blocks in React that return UI elements.
Types of Components:
- Functional Components
- Class Components
4. What is JSX?
JSX stands for JavaScript XML. It allows developers to write HTML-like syntax inside JavaScript.
Example:
function App() {
return <h1>Hello React</h1>;
}
5. What is the difference between props and state?
| Props | State |
|---|---|
| Read-only | Mutable |
| Passed from parent | Managed inside component |
| Used for communication | Used for dynamic data |
6. What are Hooks in React?
Hooks allow functional components to use state and lifecycle features.
Popular Hooks:
- useState
- useEffect
- useMemo
- useCallback
- useRef
7. What is useEffect?
useEffect is used for side effects like:
- API calls
- Timers
- Event listeners
Example:
useEffect(() => {
fetchData();
}, []);
8. What is State in React?
State stores dynamic data inside a component and causes re-rendering when updated.
Example:
const [count, setCount] = useState(0);
9. What is Conditional Rendering?
Conditional rendering means displaying UI based on conditions.
Example:
{isLoggedIn ? <Dashboard /> : <Login />}
10. What is Key in React Lists?
Keys help React identify changed items efficiently during rendering.
Example:
items.map(item => (
<li key={item.id}>{item.name}</li>
))
Why Learn React in 2026?
React remains highly demanded because:
- Huge job market
- Strong ecosystem
- Used by startups and enterprises
- Excellent performance
Final Thoughts
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:
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