Question : 1 What does JSX stand for in ReactJS?
JavaScript XML
JavaScript Extension
JavaScript XHR
JavaScript XSL
Question : 2 Which method is called once the component is mounted in ReactJS?
componentDidMount()
componentWillMount()
componentWillUnmount()
componentDidUnmount()
Question : 3 What is the purpose of state in ReactJS?
To store data that can be changed over time
To store data that remains constant throughout the component lifecycle
To handle user interactions
To manage routing in the application
Question : 4 What is the virtual DOM in ReactJS?
The actual representation of the DOM in the browser
A lightweight copy of the DOM maintained by React
A JavaScript file that defines the structure of the DOM
A set of rules for updating the DOM efficiently
Question : 5 What is a prop in ReactJS?
A function that returns React elements
A data passed from parent to child component
A built-in React method for updating the state
A way to handle user interactions in React components
Question : 6 What does the shouldComponentUpdate() method do in ReactJS?
It is called before the component is removed from the DOM
It determines if the component should re-render when its state or props change
It is called after the component is updated in the DOM
It is called before the component is rendered for the first time
Question : 7 What is a ReactJS component?
A function that returns React elements
A reusable piece of code that can be composed to create complex UIs
A JavaScript object that defines the structure of the DOM
A built-in React method for updating the state
Question : 8 What is the purpose of the setState() method in ReactJS?
To update the state of a component and trigger a re-render
To define the initial state of a component
To retrieve the current state of a component
To handle user interactions within a component
Question : 9 What is the significance of keys in ReactJS lists?
Keys are used to identify which items have changed, are added, or are removed
Keys are used to apply styling to list items
Keys are used to define the structure of a component
Keys are used to handle form input validation
Question : 10 What are React Hooks?
Functions that let you use React features without writing a class
Specialized components used for routing in React applications
Methods used for asynchronous data fetching in React components
Built-in JavaScript functions used for DOM manipulation in React
Question : 11 What is the purpose of the useEffect() hook in React?
To handle form submissions within a React component
To perform side effects in function components
To define the initial state of a component
To retrieve the current state of a component
Question : 12 What is the difference between state and props in ReactJS?
State is immutable, while props are mutable
Props are passed from parent to child components, while state is managed within a component
State is used for handling user interactions, while props are used for defining the initial state of a component
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?
To create reusable custom hooks
To share state between components without using props
To manage the lifecycle of functional components
To perform data fetching operations within a React component
Question : 14 What is the purpose of the useCallback hook in React?
To memoize expensive computations and optimize performance
To subscribe to changes in the Redux store
To define custom event handlers for user interactions
To memoize callback functions and prevent unnecessary re-renders
Question : 15 What is the purpose of the useRef hook in React?
To handle component side effects
To access the DOM element directly within functional components
To manage stateful logic in functional components
To handle asynchronous operations in React components
Question : 16 What is the difference between controlled and uncontrolled components in React?
Controlled components are managed by React, while uncontrolled components manage their own state
Controlled components use refs to access DOM elements, while uncontrolled components use state
Controlled components rely on React state to manage form data, while uncontrolled components use the DOM directly
Controlled components are stateless, while uncontrolled components are stateful
Question : 17 What is the purpose of the useMemo hook in React?
To subscribe to changes in the Redux store
To memoize expensive computations and optimize performance
To manage component lifecycle methods
To define custom event handlers for user interactions
Question : 18 What is the significance of the key prop in React lists?
Keys are used to apply styling to list items
Keys are used to define the structure of a component
Keys are used to identify which items have changed, are added, or are removed
Keys are used to handle form input validation
Question : 19 What is the purpose of the useCallback hook in React?
To memoize callback functions and prevent unnecessary re-renders
To subscribe to changes in the Redux store
To define custom event handlers for user interactions
To memoize expensive computations and optimize performance
Question : 20 What is the purpose of the useContext hook in React?
To create reusable custom hooks
To share state between components without using props
To manage the lifecycle of functional components
To perform data fetching operations within a React component
Question : 21 What is the difference between stateful and stateless components in React?
Stateful components manage their own state, while stateless components rely on props for data
Stateful components are more performant than stateless components
Stateful components are used for functional components, while stateless components are used for class components
Stateful components do not re-render when their state changes
Question : 22 What is the purpose of the useHistory hook in React Router?
To create reusable custom hooks
To share state between components without using props
To manage the browser history and navigate between pages
To perform data fetching operations within a React component
Question : 23 What is a Higher Order Component (HOC) in React?
A component that renders its children without any modifications
A function that takes a component and returns a new component with additional functionality
A component that manages global state for an application
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?
To manage component state
To perform side effects in function components
To define custom event handlers for user interactions
To subscribe to changes in the Redux store
Question : 25 What is the significance of the key prop in React lists?
Keys are used to apply styling to list items
Keys are used to define the structure of a component
Keys are used to identify which items have changed, are added, or are removed
Keys are used to handle form input validation