Top 25 React Interview Questions

Are you curious about what questions you will be asked when interviewing for a React developer role? Or did you fail any of your last React interview questions because you needed to prepare? Either way, this article is for you.

What is React?

React is a JavaScript package frequently used to create user interfaces, especially for single-page apps. Since JavaScript is used to build React, it’s important to have a solid understanding of the fundamentals of the language before using it.

React uses JSX, a language that resembles HTML but operates inside JavaScript, something that HTML doesn’t typically accomplish.

Also, Read Five MERN (MongoDB, Express, React, Node) Stack Project Ideas that would Enhance your Resume.

A React component is a piece of code that symbolizes a section of the page. Each element is a JavaScript function that produces a line of code corresponding to a web page section. Developers can use React to create web applications that modify data without refreshing the browser. You can use the large and vibrant developer community for React to learn new skills and showcase your work.

Important Interview Questions Related to React

Whether you are preparing to interview a candidate or applying for a job, here is our list of the top 25 React interview questions to help you prepare and get that role:

1. What is React, why is it used in web development, and how does it differ from other JavaScript libraries or frameworks?
2. Explain the concept of virtual DOM in React and how it contributes to performance optimization.
3. Differentiate between props and states in React. When would you use one over the other?
4. Describe the component lifecycle methods in React. What is the purpose of each method?
5. What is JSX, and how does it differ from regular JavaScript and HTML?
6. How do you create a functional component in React? Can you provide an example?
7. What are class components in React, and how do they differ from functional components?
8. How do you handle forms in React? Explain the controlled and uncontrolled components.
9. What is the purpose of keys in React lists? Why are they important?
10. What is a React Router, and how does it enable client-side routing in a React application?
11. Explain the concept of conditional rendering in React. Provide an example.
12. What are React Hooks, and why were they introduced? Provide examples of some commonly used hooks.
13. How can you pass data between parent and child components in React?
14. What is Redux, and how does it manage the state in a React application? Explain the core principles of Redux.
15. Describe the Flux architecture and its relationship to React.
16. How can you handle asynchronous operations like data fetching in React? Provide examples.
17. Explain the concept of context in React and when you might use it.
18. What are Higher Order Components (HOCs), and why are they useful in React?
19. Describe the purpose of React Fragments. When would you use them?
20. What are the key differences between React and React Native?
21. How do you optimize the performance of a React application? Mention some performance optimization techniques.
22. What tools and libraries can you use for testing React applications?
23. Explain the concept of code splitting in React. How does it benefit application performance?
24. What are the benefits of server-side rendering (SSR) in React, and how can it be implemented?
25. Discuss the importance of propTypes and defaultProps in React components.

Source: Sanjana Sanghi, software developer