Question 1

What is a React hook in React development?

Accepted Answer

React hooks are functions that let developers 'hook into' React state and lifecycle features from function components.

Answer

React hooks are components that render dynamic content in React apps.

Answer

React hooks are used for defining static data within components.

Answer

React hooks are tools for debugging React applications.

Question 2

What is the purpose of the React Router library in a React application?

Accepted Answer

React Router is used for handling navigation and routing in React applications.

Answer

React Router is used for API requests in React applications.

Answer

React Router is used for managing state in React components.

Answer

React Router is used for styling components with CSS.

Question 3

What is the main difference between state and props in React?

Accepted Answer

State is mutable data managed within a component, while props are immutable data passed from parent to child components.

Answer

State is always required in a component, while props are optional.

Answer

State is used for styling components, while props are used for managing component behavior.

Answer

State and props are essentially the same in React.

Question 4

What event is triggered when a user clicks on a button in React?

Accepted Answer

onClick

Answer

onSubmit

Answer

onHover

Answer

onChange

Question 5

What is a functional component in React?

Accepted Answer

A functional component is a simple JavaScript function that returns JSX.

Answer

A component written in a different programming language

Answer

A component that uses class-based syntax

Answer

A component with complex state management

Question 6

What is the purpose of props in a React component?

Accepted Answer

Props are used to pass data from a parent component to a child component.

Answer

Props are used for internal state management within a component.

Answer

Props are used to define the structure of a component.

Answer

Props are used to style a component with CSS.

Question 7

What lifecycle method is called immediately after a component is rendered in React?

Accepted Answer

componentDidMount

Answer

componentWillMount

Answer

componentWillUnmount

Answer

componentDidUpdate

Question 8

What does the virtual DOM do in React?

Accepted Answer

The virtual DOM is a lightweight copy of the real DOM that React uses to increase performance.

Answer

The virtual DOM is a method for storing component data.

Answer

The virtual DOM is a styling library for React.

Answer

The virtual DOM is a tool for debugging code.

Question 9

What is JSX in React?

Accepted Answer

JSX allows writing HTML in React code.

Answer

A state management library

Answer

A JavaScript framework

Answer

A CSS preprocessor

Question 10

In React, what method is used to change the state of a component?

Accepted Answer

setState

Answer

modifyState

Answer

changeState

Answer

updateState

Question 11

Which of the following is a popular JavaScript library for building user interfaces?

Accepted Answer

React

Answer

Ember

Answer

Vue

Answer

Angular

Question 12

In React, what is used to store and manage component's internal state?

Accepted Answer

State

Answer

Props

Answer

Variables

Answer

Data

Question 13

What is a React Hook used for managing state in functional components?

Accepted Answer

useState

Answer

useContext

Answer

useReducer

Answer

useEffect

Question 14

What is the virtual DOM in React?

Accepted Answer

A lightweight copy of the real DOM

Answer

An external stylesheet for React components

Answer

A programming language used in React

Answer

A routing system in React

Question 15

What command is used to create a new React application?

Accepted Answer

npx create-react-app

Answer

npm install react

Answer

create-react-app

Answer

npm start

Question 16

What feature in React allows you to pass data from a parent component to a child component?

Accepted Answer

Props

Answer

Variables

Answer

Attributes

Answer

State

Question 17

What lifecycle method in React is called after a component has been rendered for the first time?

Accepted Answer

componentDidMount

Answer

componentWillUnmount

Answer

componentWillMount

Answer

componentDidUpdate

Question 18

What is JSX in React?

Accepted Answer

JavaScript XML

Answer

Java Extension

Answer

JavaScript Extension

Answer

JSON XML

Question 19

What is a React component?

Accepted Answer

A reusable piece of code that represents a part of the user interface

Answer

A built-in function in React

Answer

An external library in React

Answer

A variable in React

Question 20

What is the purpose of the useEffect hook in React?

Accepted Answer

To perform side effects in function components

Answer

To create reusable logic in function components

Answer

To handle AJAX requests in function components

Answer

To manage state in function components

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