Master your interview by practicing the React Interview Questions

Interviews are more than just a gateway to new opportunities—they are your chance to showcase your skills, confidence, and problem-solving abilities to potential employers. When it comes to React, React Router, State Management, and React Hooks, the competition is fierce, and the expectations are high.

To stand out and make a lasting impression, learners must go beyond theoretical knowledge. Practical expertise, hands-on problem-solving, and a clear understanding of key concepts are essential. That’s why I’ve created a list of must-practice interview questions to help you succeed in your journey.

Below is the list of 100 top-level interview questions from React, React Router, State Management, and React Hooks that are suitable for interviews at multinational companies:

React (Basics)

1. What are the key features of React, and how does it differ from other frameworks like Angular or Vue?
2. Explain the concept of Virtual DOM and how it improves React's performance.
3. What are React components? Differentiate between class components and functional components.
4. What is JSX? Why do we use it in React?
5. Explain the lifecycle methods of class components. How are they replaced in functional components?
6. What are React fragments, and why are they used?
7. How does React handle conditional rendering? Provide examples.
8. What is the purpose of keys in React? Why are they important for lists?
9. Explain the concept of Higher-Order Components (HOCs) in React.
10. What are controlled and uncontrolled components in React? Provide examples.
11. What is the significance of the React.StrictMode component?
12. How does React handle performance optimization? Discuss techniques like memoization and lazy loading.
13. What are portals in React? How and why are they used?
14. How would you debug a React application?
15. What is server-side rendering (SSR) in React, and how does it differ from client-side rendering (CSR)?
16. What are error boundaries in React? How do they work?

React (Concept-Based and Practical)

1. How would you handle performance issues caused by excessive re-renders in a React component?
2. How can you implement lazy loading for images in React?
3. Demonstrate how you would debounce an input field in a React form.
4. How would you dynamically import a component in React?
5. Write a React code snippet to toggle a dark mode feature.
6. How can you share state between sibling components in React?
7. How would you implement infinite scrolling in a React application?
8. Write a React snippet to implement drag-and-drop functionality for a list of items.
9. How do you handle component cleanup when using event listeners in functional components?
10. How would you programmatically focus an input field in React?
11. Implement a counter component with increment and decrement buttons.
12. Write code to dynamically add and remove input fields in a form.
13. How would you create a reusable button component with dynamic styles?
14. Implement a simple to-do list using functional components.
15. How do you handle conditional styling in React?
16. How would you prevent re-renders in a component when the props haven’t changed?
17. Write a snippet to fetch and display data using fetch in a React component.
18. How can you handle file uploads in a React application?
19. Write code to highlight the currently active menu item in a navigation bar.
20. How do you React Router handle errors in a React component without using error boundaries?

React Router (Basics)

1. What is React Router, and why is it used in React applications?
2. How does React Router handle dynamic routing?
3. What is the difference between <BrowserRouter> and <HashRouter> in React Router?
4. How would you implement nested routes in React Router?
5. What is the difference between <Link> and <NavLink> in React Router?
6. Explain the purpose of the useParams hook in React Router.
7. How can you implement route protection (protected routes) in a React application?
8. What is the significance of the useHistory (or useNavigate) hook in React Router v6?
9. How can you handle 404 pages (not found routes) in React Router?
10. Discuss how React Router enables lazy loading of components.
11. What is the useLocation hook, and how is it used?
12. Explain the concept of redirecting routes in React Router.

React Router (Concept-Based and Practical)

1. How do you implement breadcrumbs in a React Router application?
2. Write a code snippet to navigate programmatically on a button click.
3. How can you pass query parameters in a React Router URL?
4. Implement a route with dynamic parameters and fetch data based on the parameter.
5. How would you protect a route and redirect unauthorized users to a login page?
6. Write a snippet to prefetch data before rendering a route.
7. How can you implement a "Back to Previous Page" button in React Router?
8. How would you handle navigation between nested routes?
9. Implement a fallback UI for a route when data is loading.
10. How can you animate transitions between routes in React Router?

State Management (Basics)

1. What is state management in React, and why is it important?
2. What is the difference between local state and global state in React?
3. Compare and contrast Context API with state management libraries like Redux.
4. Explain the purpose of Redux. How does it manage the state of a React application?
5. What are the key principles of Redux?
6. How does the Redux store work, and how do you connect it to a React application?
7. Explain the difference between synchronous and asynchronous actions in Redux.
8. What are middleware functions in Redux? Why are they used?
9. How does Redux Toolkit simplify state management in Redux?
10. What is the significance of the Provider component in Context API and Redux?
11. How does React Query differ from Redux for managing asynchronous data?
12. What are selectors in Redux, and how do they improve performance?

State Management (Concept-Based and Practical)

1. How would you manage a complex form's state with multiple inputs using local state?
2. Write a snippet to update a specific item in an array stored in state.
3. How do you manage shared state between multiple components without Redux?
4. Implement a search filter using local state and a list of items.
5. How can you update the state of a parent component from a child component?
6. Demonstrate how you would manage a counter state using Redux.
7. How can you reset state in Redux to its initial value?
8. Write a selector function to retrieve filtered data from the Redux store.
9. How do you handle optimistic updates in Redux or any state management library?
10. Implement a global notification system using Context API.

React Hooks (Basics)

1. What are React hooks, and why were they introduced?
2. Explain the useState hook. How does it manage component state?
3. What is the useEffect hook? How does it replace lifecycle methods?
4. Explain the useContext hook with an example.
5. What is the useRef hook, and how is it different from createRef?
6. How does the useMemo hook optimize performance in React applications?
7. What is the useCallback hook, and when should you use it?
8. Explain the useReducer hook. How is it different from useState?
9. What is the purpose of the useImperativeHandle hook in React?
10. What are custom hooks in React? How and why would you create one?

React Hooks (Concept-Based and Practical)

1. How would you implement a countdown timer using useState and useEffect?
2. Write a custom hook to fetch and cache data from an API.
3. How would you persist state across sessions using localStorage and useEffect?
4. Write a custom hook for form validation in React.
5. Implement a feature to toggle a sidebar using useReducer.
6. How would you implement a throttling function in a React component using hooks?
7. Write code to measure the size of a DOM element using useRef.
8. How would you synchronize data between a parent and child component using useContext?
9. Implement a React feature to track whether the user is online or offline using hooks.
10. How can you handle animations in React using the useEffect hook?

Why Practice These Questions?

1. Build Confidence: Practicing these questions will boost your confidence by helping you solve real-world problems that employers often ask during technical interviews.
2. Develop Practical Skills: The questions focus on conceptual clarity and practical implementation—skills that are critical for React developers working on large-scale applications.
3. Stand Out in Interviews: Employers value candidates who demonstrate a deep understanding of topics like React lifecycle, routing, state management, and hooks. These questions are tailored to help you showcase that expertise.
4. Stay Updated with Industry Standards: These questions are designed to cover the latest features and trends in React, ensuring you’re always in sync with what top companies expect from candidates.
5. Crack Technical Rounds Effectively: MNCs and product-based companies often test candidates on problem-solving and coding skills. These questions will prepare you for coding challenges and practical implementations.

Primary Objective of Sharing These Questions

The goal of this article is not just to provide questions but to:

• Empower learners to prepare better for interviews.
• Guide aspiring developers to master React and its ecosystem.
• Bridge the gap between knowledge and practical application.
• Motivate students and professionals to push their boundaries and aim higher in their careers.

Who Should Practice These Questions?

• Students aiming to crack technical rounds at top companies.
• Freshers preparing for their first job interview.
• Professionals transitioning into React development.
• Experienced developers looking to polish their React skills and stay relevant.

Your Journey to Success Starts Here

By practicing these questions, you’ll not only prepare for interviews but also become a more confident and competent developer. Remember, it’s not just about answering questions—it’s about showcasing your ability to think critically, solve problems, and add value to any team.

I believe that with the right preparation and determination, you can achieve your dream role. Start practicing today, and let’s work together to make your aspirations a reality!

Feel free to explore the questions I’ve shared below and share your feedback. Your growth and success are my biggest motivations!

Good luck with your learning and interviews! ??

Author: Mohit Singh, Director, Learn2Earn Labs