Question : 1 What does JSX stand for in ReactJS?

• A

  JavaScript XML

• B

  JavaScript Extension

• C

  JavaScript XHR

• D

  JavaScript XSL

Question : 2 Which method is called once the component is mounted in ReactJS?

• A

  componentDidMount()

• B

  componentWillMount()

• C

  componentWillUnmount()

• D

  componentDidUnmount()

Question : 3 What is the purpose of state in ReactJS?

• A

  To store data that can be changed over time

• B

  To store data that remains constant throughout the component lifecycle

• C

  To handle user interactions

• D

  To manage routing in the application

Question : 4 What is the virtual DOM in ReactJS?

• A

  The actual representation of the DOM in the browser

• B

  A lightweight copy of the DOM maintained by React

• C

  A JavaScript file that defines the structure of the DOM

• D

  A set of rules for updating the DOM efficiently

Question : 5 What is a prop in ReactJS?

• A

  A function that returns React elements

• B

  A data passed from parent to child component

• C

  A built-in React method for updating the state

• D

  A way to handle user interactions in React components

Question : 6 What does the shouldComponentUpdate() method do in ReactJS?

• A

  It is called before the component is removed from the DOM

• B

  It determines if the component should re-render when its state or props change

• C

  It is called after the component is updated in the DOM

• D

  It is called before the component is rendered for the first time

Question : 7 What is a ReactJS component?

• A

  A function that returns React elements

• B

  A reusable piece of code that can be composed to create complex UIs

• C

  A JavaScript object that defines the structure of the DOM

• D

  A built-in React method for updating the state

Question : 8 What is the purpose of the setState() method in ReactJS?

• A

  To update the state of a component and trigger a re-render

• B

  To define the initial state of a component

• C

  To retrieve the current state of a component

• D

  To handle user interactions within a component

Question : 9 What is the significance of keys in ReactJS lists?

• A

  Keys are used to identify which items have changed, are added, or are removed

• B

  Keys are used to apply styling to list items

• C

  Keys are used to define the structure of a component

• D

  Keys are used to handle form input validation

Question : 10 What are React Hooks?

• A

  Functions that let you use React features without writing a class

• B

  Specialized components used for routing in React applications

• C

  Methods used for asynchronous data fetching in React components

• D

  Built-in JavaScript functions used for DOM manipulation in React

Question : 11 What is the purpose of the useEffect() hook in React?

• A

  To handle form submissions within a React component

• B

  To perform side effects in function components

• C

  To define the initial state of a component

• D

  To retrieve the current state of a component

Question : 12 What is the difference between state and props in ReactJS?

• A

  State is immutable, while props are mutable

• B

  Props are passed from parent to child components, while state is managed within a component

• C

  State is used for handling user interactions, while props are used for defining the initial state of a component

• D

  State is used for functional components, while props are used for class components

Question : 13 What is the purpose of the useContext hook in React?

• A

  To create reusable custom hooks

• B

  To share state between components without using props

• C

  To manage the lifecycle of functional components

• D

  To perform data fetching operations within a React component

Question : 14 What is the purpose of the useCallback hook in React?

• A

  To memoize expensive computations and optimize performance

• B

  To subscribe to changes in the Redux store

• C

  To define custom event handlers for user interactions

• D

  To memoize callback functions and prevent unnecessary re-renders

Question : 15 What is the purpose of the useRef hook in React?

• A

  To handle component side effects

• B

  To access the DOM element directly within functional components

• C

  To manage stateful logic in functional components

• D

  To handle asynchronous operations in React components

Question : 16 What is the difference between controlled and uncontrolled components in React?

• A

  Controlled components are managed by React, while uncontrolled components manage their own state

• B

  Controlled components use refs to access DOM elements, while uncontrolled components use state

• C

  Controlled components rely on React state to manage form data, while uncontrolled components use the DOM directly

• D

  Controlled components are stateless, while uncontrolled components are stateful

Question : 17 What is the purpose of the useMemo hook in React?

• A

  To subscribe to changes in the Redux store

• B

  To memoize expensive computations and optimize performance

• C

  To manage component lifecycle methods

• D

  To define custom event handlers for user interactions

Question : 18 What is the significance of the key prop in React lists?

• A

  Keys are used to apply styling to list items

• B

  Keys are used to define the structure of a component

• C

  Keys are used to identify which items have changed, are added, or are removed

• D

  Keys are used to handle form input validation

Question : 19 What is the purpose of the useCallback hook in React?

• A

  To memoize callback functions and prevent unnecessary re-renders

• B

  To subscribe to changes in the Redux store

• C

  To define custom event handlers for user interactions

• D

  To memoize expensive computations and optimize performance

Question : 20 What is the purpose of the useContext hook in React?

• A

  To create reusable custom hooks

• B

  To share state between components without using props

• C

  To manage the lifecycle of functional components

• D

  To perform data fetching operations within a React component

Question : 21 What is the difference between stateful and stateless components in React?

• A

  Stateful components manage their own state, while stateless components rely on props for data

• B

  Stateful components are more performant than stateless components

• C

  Stateful components are used for functional components, while stateless components are used for class components

• D

  Stateful components do not re-render when their state changes

Question : 22 What is the purpose of the useHistory hook in React Router?

• A

  To create reusable custom hooks

• B

  To share state between components without using props

• C

  To manage the browser history and navigate between pages

• D

  To perform data fetching operations within a React component

Question : 23 What is a Higher Order Component (HOC) in React?

• A

  A component that renders its children without any modifications

• B

  A function that takes a component and returns a new component with additional functionality

• C

  A component that manages global state for an application

• D

  A component that renders a loading indicator while waiting for data to load

Question : 24 What is the purpose of the useEffect hook in React?

• A

  To manage component state

• B

  To perform side effects in function components

• C

  To define custom event handlers for user interactions

• D

  To subscribe to changes in the Redux store

Question : 25 What is the significance of the key prop in React lists?

• A

  Keys are used to apply styling to list items

• B

  Keys are used to define the structure of a component

• C

  Keys are used to identify which items have changed, are added, or are removed

• D

  Keys are used to handle form input validation