React.js Quiz

In this React.js Quiz section – every Question Carries 2 Marks. If any question is wrong then two marks will be deducted.

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React.js Quiz

1 / 50

What is React.js primarily used for?

Server-side scripting

Building user interfaces

Data visualization

Database management

2 / 50

Which of the following represents a component in React.js?

function

object

class

array

3 / 50

What is JSX in React.js?

A database query language

A templating engine

A syntax extension for JavaScript

A version control system

4 / 50

Which method is used to render a React component into the DOM?

renderComponent()

mountComponent()

ReactDOM.render()

attachComponent()

5 / 50

What does setState() do in React?

Updates the component's state

Re-renders the component

Fetches data from an API

Initializes the component

6 / 50

Which lifecycle method is invoked immediately after a component is mounted?

componentDidMount()

componentWillMount()

componentDidUpdate()

componentWillUpdate()

7 / 50

In React, how do you pass data to a child component from a parent component?

Using props

Using state

Using Redux

Using refs

8 / 50

What is the purpose of key prop in React lists?

Adds a unique identifier to elements

Controls element visibility

Sets default props

Initializes state

9 / 50

Which hook is used to add state to a functional component in React?

useState()

useEffect()

useReducer()

useContext()

10 / 50

What is the correct way to conditionally render content in React?

Using if-else statements

Using ternary operators

Using switch-case statements

Using for loops

11 / 50

What is a higher-order component (HOC) in React?

A component with complex state

A component that renders other components

A function that returns a component

A component that manages routing

12 / 50

How do you handle events in React?

Using event listeners

Using event delegation

Using onClick props

Using inline event handlers

13 / 50

What is the purpose of dangerouslySetInnerHTML in React?

Injects raw HTML into a component

Escapes special characters

Sets component styles

Controls component visibility

14 / 50

Which method is used to fetch data from an API in React?

fetch()

axios()

get()

request()

15 / 50

What does React Router do?

Manages global state

Handles routing in a React application

Optimizes performance

Validates form data

16 / 50

What is the purpose of componentDidUpdate() lifecycle method?

Invoked after a component is mounted

Invoked before a component is updated

Invoked after a component is updated

Invoked when a component is unmounted

17 / 50

What is a controlled component in React?

A component that manages its own state

A component that does not render in the DOM

A component that relies on props

A component that uses unidirectional data flow

18 / 50

Which method is used to stop the propagation of an event in React?

event.stopPropagation()

event.preventDefault()

event.stopEvent()

stopPropagation()

19 / 50

What is the purpose of React.Fragment in React?

Represents a single DOM element

Groups multiple components without adding extra nodes to the DOM

Handles forms in React

Encapsulates styles

20 / 50

Which method is used to update the state based on the previous state in React?

setState()

updateState()

prevState()

setState((prevState) => { })

21 / 50

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

Manages component state

Handles side effects in functional components

Renders JSX elements

Adds event listeners

22 / 50

Which prop is used to conditionally apply styles in React?

className

style

css

applyStyle

23 / 50

What is Redux in the context of React?

A server-side rendering framework

A state management library

A form validation library

A routing library

24 / 50

How do you pass data from a child component to a parent component in React?

Using props

Using state

Using Redux

Using refs

25 / 50

What does the useReducer() hook do in React?

Adds state management to a functional component

Manages side effects in a component

Updates component props

Defines a higher-order component

26 / 50

Which method is used to perform a shallow comparison of props and state in React?

shallowCompare()

isEqual()

shouldComponentUpdate()

compareProps()

27 / 50

What is the purpose of props.children in React?

Represents child components

Represents parent components

Represents child elements or text within a component

Handles form input validation

28 / 50

Which method is used to schedule a task to be run at a later time in React?

setTimeout()

setInterval()

requestAnimationFrame()

wait()

29 / 50

What is the purpose of React.memo() in React?

Memoizes functional components for performance optimization

Memoizes class components for performance optimization

Clears component cache

Renders components lazily

30 / 50

What is the purpose of React.PureComponent?

Manages component state

Optimizes component rendering

Handles asynchronous data fetching

Applies CSS styles to components

31 / 50

What is the purpose of React.createRef()?

Creates a new React component

reates a reference to a DOM element or React component

Initializes component state

Manages global state

32 / 50

How do you handle form input in React?

Using event handlers

Using Redux

Using state

Using refs

33 / 50

What is the purpose of React.cloneElement()?

Creates a new instance of a React component

Clones and modifies a React element with new props

Renders a child component

Applies styles to a React component

34 / 50

Which method is used to perform a deep comparison of props and state in React?

deepCompare()

isEqual()

shouldComponentUpdate()

compareProps()

35 / 50

What is the purpose of React.forwardRef()?

Forwards DOM refs to child components

Forwards component props to child components

Creates a new ref object

Manages asynchronous tasks

36 / 50

What is the correct way to import a React component?

import MyComponent from './MyComponent';

include MyComponent from './MyComponent';

require MyComponent from './MyComponent';

from MyComponent import *;

37 / 50

What does React Router's <Link> component do?

Renders a button

Renders a navigation link

Fetches data from an API

Manages local state

38 / 50

What is the purpose of React.useState() hook?

Adds state management to a functional component

Adds routing to a component

Updates component props

Initializes component state

39 / 50

Which method is used to create a portal in React?

ReactDOM.createPortal()

React.createPortal()

createPortal()

createDOMPortal()

40 / 50

What is the purpose of React.Suspense component?

Suspends data fetching in React components

Suspends component rendering

Suspends state updates

Suspends event handling

41 / 50

How do you conditionally render components in React?

Using if-else statements

Using ternary operators

Using switch-case statements

Using loops

42 / 50

What is the purpose of React.useEffect() hook in React functional components?

Adds event listeners to components

Handles side effects in components

Initializes component state

Manages form input

43 / 50

Which method is used to create a custom hook in React?

createHook()

useHook()

React.createHook()

React.useHook()

44 / 50

What does the React.StrictMode component do?

Enforces strict typing in React components

Enables strict mode for rendering

Optimizes component performance

Validates props and state

45 / 50

What is the purpose of React.Fragment in React components?

Represents a single DOM element

Groups multiple elements without adding extra nodes to the DOM

Renders hidden components

Applies global styles

46 / 50

What is the purpose of React.memo() in functional components?

Memoizes components for performance optimization

Adds memoization to state updates

Prevents component rendering

Applies CSS styles to components

47 / 50

Which method is used to handle async operations in React functional components?

asyncEffect()

useEffect()

handleAsync()

fetchAsync()

48 / 50

What is the purpose of React.lazy() and Suspense in React?

Lazily loads components

Optimizes component rendering

Delays component updates

Implements lazy loading of images

49 / 50

Which tool is commonly used for managing state in large React applications?

Redux

React Router

Jest

Axios

50 / 50

What is the purpose of the withRouter higher-order component (HOC) in React Router?

Adds routing capabilities to a component

Wraps components in a router context

Provides access to routing props in components

Applies global styles to components

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The average score is 60%

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