Top 51 React js Interview Questions And Answers 2024

1. What Is React?
2. When Reactjs released?
3. What Is the current stable version of Reactjs?
4. What Is the Repository URL of Reactjs?
5. How Is React different?
6. Why Reactjs Is used?
7. What do you mean by Reactjs?
8. What Are the features of React?
9. What Are the Advantages of Reactjs?
10. What Are the limitations of Reactjs?Do you think Reactjs has any limitations? If so, tell a few?
11. Does Reactjs use HTML?
12. What Is the life Cycle of Reactjs components?
13. What Is JSX?
14. Why can’t browsers read JSX?
15. What Are the differences in between Real DOM and Virtual DOM?
16. Is it possible to nest JSX elements into other JSX elements?
17. What Is a state in Reactjs and how is it used?
18. What Are the Differentiate between stateful and stateless components?
19. What Are the purpose of render() in React?
20. What are Custom Hooks?
21. What Are the difference between pros and state?
22. Is it possible to display props on a parent component?
23. What Is Synthetic event?
24. What Are the differences between Controlled and Uncontrolled Components?
25. What Is Higher Order Components (HOC)?
26. What Is Component in Reactjs?
27. What Is Controllable Component in Reactjs?
28. What Is Uncontrollable Component in Reactjs?
29. What Are Pure Components?
30. How to update the State of the Component in Reactjs?
31. What Are the Component Life Cycle methods in Reactjs?
32. What Are the methods called when Component is created or while inserting it to DOM?
33. What Are the methods called when State or Props of the Component is changed?
34. In which lifecycle event do you make AJAX requests and why?
35. What Is React Router?
36. Why do we need a Router in Reactjs?
37. When would you use a Class Component over a Functional Component?
38. What Is difference between setState and forceUpdate () and findDOMNode () in Reactjs?
39. How to use Loop in Reactjs?
40. How to set focus in Reactjs?
41. What Are the components in Flux architecture?
42. What Are the popular libraries used for Flux?
43. What Are refs in React and why are they important?
44.  What Are keys in React and why are they important?
45. What Is React Lifecycle Components?
46. What are props in React?
47. Explain React state and props.
48.  Explain about types of side effects in React component.
49. What is prop drilling in React?
50.  What is React Hooks?
51. What are the rules that must be followed while using React Hooks?

React js Interview Questions And Answers

1. What Is React?

Answer: React is an open-source JavaScript library developed by Facebook for building user interfaces or UI components. It is widely used for creating interactive and dynamic single-page applications.

2. When was React.js released?

Answer: React.js was first released by Facebook in March 2013.

3.What Is the current stable version of React.js?

Answer: The stable version of React.js can change over time. It’s recommended to check the official React website or the GitHub repository for the most up-to-date information on the current stable version.

4.What Is the Repository URL of React.js?

Answer: The official GitHub repository for React.js is https://github.com/facebook/react.

5. How Is React different?

Answer: React is different because it utilizes a virtual DOM for efficient updates, employs a component-based architecture for reusability, and introduces JSX, a syntax extension for JavaScript that allows for declarative UI development.

6.Why is React.js used?

Answer: React.js is used for building user interfaces with a focus on creating reusable UI components. It simplifies the process of building and maintaining large-scale applications, providing efficient rendering and a modular development approach.

7.What do you mean by React.js?

Answer: React.js is a JavaScript library for building user interfaces. It enables the creation of dynamic and responsive UIs by efficiently updating the DOM through the use of a virtual DOM.

8.What Are the features of React?

Answer: Key features of React include a virtual DOM for efficient updates, JSX for declarative syntax, component-based architecture for reusability, unidirectional data flow, and the ability to work with both client-side and server-side rendering.

9.What Are the Advantages of React.js?

Answer: Advantages of React.js include improved performance with a virtual DOM, a component-based structure for reusability, strong community support, one-way data binding for predictable updates, and compatibility with other libraries or frameworks.

10.What Are the limitations of React.js?

Answer: React.js has few limitations, such as a steep learning curve for beginners, frequent updates leading to version compatibility issues, and the need for additional libraries for certain functionalities like routing and state management.