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Top 41 React JS Interview Questions and Answers

30/Sep/2020 | 10 minutes to read

Here is a List of essential React JS Interview Questions and Answers for Freshers and mid level of Experienced Professionals. All answers for these React JS questions are explained in a simple and easiest way. These questions will help you to clear your next Job interview.

Best Answers to React JS Interview Questions

These interview questions are targeted for React.js developers. You should know the answers of these React questions to clear the interview.

1. What is React?

React is a JavaScript based front-end and open-source library that is used to build UI components or user interfaces. It's developed and maintained by Facebook. React or React.js is used for SPA (Single Page Application) and mobile application development. It's a community of individual developers.

2. What are the advantages and disadvantages of React JS?

3. How will you differentiate React JS and React Native?

React.js is a JavaScript based library to build UI components or user interfaces or UI layer for browser applications. It's just responsible for UI rendering (only View part from MVC Architecture).
ReactNative is a platform to develop cross platform, native mobile applications. It's a framework that comes with many native components and modules to develop high performance mobile applications.

4. How does React work?

5. Differentiate state and props.

6. Explain ref keyword. What is the use of ref in React?

7. Explain dirty checks in React.

8. What is prop drilling? How to avoid it?

9. What is Virtual DOM? How it works in React?

10. Explain React.createClass.

11. Explain the React DOM. How it is different from React?

12. What is the difference between class component and functional component?

13. Explain Event handling in React.

14. What is the use of StrictMode component?

15. What are controlled components in React?

16. Explain Higher Order Components (HOCs). How to create it?

17. What is create-react-app command?

18. What is the use of JSX?

19. What is Redux?

20. What is the use of Redux Thunk?

21. How PureComponent is different from Component?

22. Why do we need keys in React?

23. How would decide between React JS library and Angular framework?

24. Explain the advantages and disadvantages of shallow rendering components in tests?

25. Explain the use of super() constructor?

26. What is the use of React.createElement?

27. How to update state so that it can re-render the component? Or explain setState() method.

28. Explain ReactJS component lifecycle.

29. What is the use of three dots (...) in React?

30. Explain React Hooks.

31. What are the advantages of Hooks?

32. What is the use of useState() in React?

33. Explain this keyword.

34. Differentiate controller vs uncontrolled component.

35. Explain React context.

36. Explain React Fiber.

37. How to add attributes to components conditionally?

38. What is the difference between using constructor vs getInitialState in React JS?

39. How to update parent's state in React JS?

40. How will you decide to use class based components vs functional components?

41. What is most common approach to apply styles to react application.

Some General Interview Questions for React JS

1. How much will you rate your self in React JS?

When you attend an interview, Interviewer may ask you to rate your self in specific Technology like React JS, So It's depend on your knowledge and work experience in React JS.

2. What challenges did you face while working on React JS?

This question may be specific to your technology and completely depends on your past work experience. So you need to just explain the challenges you faced related to React JS in your Project.

3. What was your role in last Project related to React JS?

It's based on your role and responsibilities assigned to you and what functionality you implemented using React JS in your project. This question is generally asked in every interview.

4. How much experience do you have in React JS?

Here you can tell about your overall work experience on React JS.

5. Have you done any React JS Certification or Training?

It's depend on candidate like you have done any React JS training or certification. Certifications or trainings are not essential but good to have.


We have covered some frequently asked React JS Interview Questions and Answers to help you for your Interview. All these Essential React JS Interview Questions are targeted for mid level of experienced Professionals and freshers.
While attending any React JS Interview if you face any difficulty to answer any question please write to us at Our IT Expert team will find the best answer and will update on portal. In case if we find any new React JS questions, we will update the same here.

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