250+ React Js MCQ With Online Practice Test

React.js, often simply called React, is a highly popular JavaScript library for building user interfaces. Developed and maintained by Facebook, React is renowned for its component-based architecture and the ability to efficiently update and render components when data changes. It is a foundational tool for developing modern web and mobile applications, allowing developers to create dynamic and interactive user interfaces with ease. React's vast ecosystem, including tools like React Native for mobile app development, makes it a top choice for frontend development and a key player in the world of web technologies.

Practice Test

1. What is React.js primarily used for?

Answer: Front-end web development

2. Who developed React.js?

Answer: Facebook

3. Which programming language is commonly used to write React.js applications?

Answer: JavaScript

4. What is the term used to describe React's ability to update only changed parts of the user interface?

Answer: Virtual DOM

5. What is JSX in React.js?

Answer: A syntax extension for JavaScript

6. Which virtual DOM library is used by React.js?

Answer: ReactDOM

7. What is the primary function of ReactDOM in a React application?

Answer: Virtual DOM manipulation

8. In React, what are components?

Answer: Functional units of code

9. What is the purpose of React Native?

Answer: Building native mobile apps

10. Which of the following is NOT a core concept of React?

Answer: Two-way data binding
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React Js Multiple Choice Questions React Js MCQ React Js Interview Questions With Answers