React js interview questions and Answers

Last updated on Feb 10, 2024
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React js interview questions

ReactJS is a JavaScript library for building reusable User interface components. It is a template-based language combined with different functions that support the HTML. Our recently updated React Interview Questions can help you crack your next interview. This means the result of any React's operation is an HTML code. You can use ReactJS to build all kinds of single-page applications.

Short Questions About React
What is the latest version of React? 18.0, released on March 29, 2022.
When was React first released? 29th May 2013
React JS is Created By Jordan Walke
License of ReactJS MIT License

React Developer Interview Questions

Here in this article, we will be listing frequently asked React js interview questions and Answers with the belief that they will be helpful for you to gain higher marks. Also, to let you know that this article has been written under the guidance of industry professionals and covered all the current competencies.

Q21. What is Flux?

Flux is an illustration that helps to maintain a unidirectional data stream. It also controls construed data unique fragments and makes them interface without creating issues. The configuration of Flux is insipid and is not specific to applications.

Q22. What is meant by pooling?

The server needs to be regularly monitored for updates. The aim is to check for the presence of new comments. This process is considered as pooling. It checks for the updates almost every 5 seconds. Pooling helps keep an eye on the users and ensure there is no negative information on servers.

Q23. In what cases would you use a Class Component over a Functional Component?

If your component has a state or lifecycle method, use Class component. Else, a Functional component.

Q24. What can you do if the expression contains more than one line?

Enclosing the multi-line JSX expression is the best option. Sometimes it becomes necessary to avoid multi-lines in order to perform the task reliably and for getting the expected results.

Q25. Is it possible to use the word Class in JSX?

No. This is because the word Class is an occupied word in JavaScript. If you use the word Class JSX will get translated to JavaScript.

Note: Before getting confused with the plethora of react coding interview questions, you need to ensure the basics. This question will help you to understand the core basics of react and make you even more confident enough to jump onto the advanced questions.

Q26. Is it possible to display props on a parent component?

Yes. This is a complex process, and the best way to do it is by using a spread operator.

Q27. What is React?

React is a JavaScript Library which is used to show content to user and handle user interaction.

Q28. What is Component?

Component is a building block of any React app which is made by either JavaScript Function of Class. Ex. Header Component, Footer Component etc.

There are two types of Components.
  • Function Based Component
  • Class Based Component
Q29. What are Class Based Component?

Class Based Component is the JavaScript Class. In these Components we extends the JavaScript predefined class into our component.


Import React,{Component} from ‘react’;

class ABC extends Component {




       <h1>Hello World</h1>




export default ABC;

Q30. What is a Higher Order Component (HOC)?

A higher-order component or HOC in React is basically an advanced technique used for reusing component logic. HOCs are not a part of the React API. They are a pattern emerging from the React's compositional nature.

Higher Order Component in React
A higher-order component is any function that takes an element and returns it with a new item.

Top 20 React.js Interview Questions

Here you will find the list of Top React interview questions, which were written under the supervision of industry experts. These are the most common questions and usually asked in every interview for the role of the React Developers.

  • What is HOC?
  • What are the difference between Rest and Spread Operator?
  • What are the key benefits of using Arrow functions?
  • What is Pure Component?
  • What are Controlled and Uncontrolled components with example?
  • What is Refs?
  • What is the difference between class based component & function based components?
  • How to work React?
  • Why virtual Dom is faster than real dom?
  • How does virtual Dom work in react?
  • What are the difference between null & undefined?


Now that you have read all the react questions, it is time for you to go towards the next level. Applying for a developer position would require you to actually code and not just give answers to theoretical questions.

That’s why you should enhance your skills by complementing the above react developer interview questions with a practical mindset. Start coding small stuff, get your concepts crystal clear. It’s all about how you can apply your knowledge in different projects. Code and code, that’s the secret to winning the dream job!

Reviewed and verified by Umesh Singh
Umesh Singh

My name is Umesh Singh having 11+ experience in Node.JS, React JS, Angular JS, Next JS, PHP, Laravel, WordPress, MySQL, Oracle, JavaScript, HTML and CSS etc. I have worked on around 30+ projects. I lo...