React js multiple choice questions with answers

Explore a comprehensive collection of react js mcq questions. Test your knowledge and understanding of React.js concepts, from component lifecycle to state management and JSX syntax. Enhance your skills, prepare for interviews, or assess your proficiency in this popular JavaScript library. 

MCQss provide a collection of MCQs specifically focused on testing one's knowledge and understanding of React.js concepts. These react js multiple choice questions with answers likely cover a wide range of topics, such as component lifecycle, state management, JSX syntax, event handling, and more.

 



Here are some react js assessment multiple choice questions along with their answers:


1. What is React.js?

   a) A back-end programming language

   b) A front-end JavaScript library

   c) A database management system

   d) A mobile application framework

   Answer: b


2. Which company developed React.js?

   a) Facebook

   b) Google

   c) Microsoft

   d) Apple

   Answer: a


3. What is JSX in React.js?

   a) A programming language

   b) A query language

   c) A templating engine

   d) A syntax extension for JavaScript

   Answer: d


4. In React.js, what does the virtual DOM represent?

   a) The actual HTML structure of a web page

   b) A lightweight representation of the DOM

   c) The CSS styles applied to a web page

   d) The server-side rendering of a web page

   Answer: b


5. Which component lifecycle method is called immediately after a component is rendered?

   a) componentDidMount

   b) componentDidUpdate

   c) componentWillMount

   d) componentWillReceiveProps

   Answer: a


6. How can you update the state of a component in React.js?

   a) Using setState()

   b) Using this.state()

   c) Using this.setState()

   d) Using props

   Answer: c


7. What is the purpose of the key prop in React.js?

   a) It specifies the component's display order

   b) It provides a unique identifier for each element in an array

   c) It defines the component's state

   d) It handles keyboard events in a component

   Answer: b


8. What is the purpose of the render() method in a React component?

   a) It handles user input events

   b) It updates the component's state

   c) It defines the component's HTML output

   d) It fetches data from a server

   Answer: c


9. What is the role of the constructor() method in a React component?

   a) It initializes the component's state

   b) It defines the component's HTML structure

   c) It renders the component to the DOM

   d) It handles component events

   Answer: a


10. What is the purpose of React Router in React.js?

    a) It manages the state of React components

    b) It handles HTTP requests in a React application

    c) It provides navigation functionality for single-page applications

    d) It optimizes the rendering performance of React components

    Answer: c


11. Which of the following is NOT a valid way to create a React component?

    a) class MyComponent extends React.Component {}

    b) function MyComponent() {}

    c) const MyComponent = () => {}

    d) <MyComponent />

    Answer: d


12. What is the recommended way to make AJAX requests in React.js?

    a) Using the fetch() API

    b) Using the jQuery.ajax() method

    c) Using the axios library

    d) Using the XMLHttpRequest object

    Answer: a


13. What does the term "unidirectional data flow" mean in React.js?

    a) Data flows in both directions between components

    b) Data flows from parent components to child components only

    c) Data flows from child components to parent components only

    d) Data flows randomly between components

    Answer: b


You can also practice our free javascript mcq questions:

Javascript multiple choice questions

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