Quiz | Croma Campus

Which of the following statements about React Hooks is true?

They only work with class components
They allow you to use state and other React features without writing a class
They are used to define component lifecycle methods
They are deprecated in the latest version of React

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In React, what is the purpose of keys in arrays of elements?

To uniquely identify each element in the array
To provide styling information
To store component data
To specify element hierarchy

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How do you handle events in React?

Using addEventListener
Using on prefix in JSX
Using handleEvent method
Using event method

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How do you create a custom Hook in React?

By extending the React.Component class
By using the 'createHook' function
By prefixing the function name with 'use'
By importing the 'CustomHook' module

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What is the purpose of useMemo hook?

To memoize functions
To memoize values
To handle side effects
To fetch data

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Which of the following is NOT a valid lifecycle method in React?

componentWillMount()
componentWillUpdate()
componentDidReceiveProps()
componentWillUnmount

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What is the purpose of useReducer hook?

To manage state in complex components
To handle side effects
To fetch data
To define context

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How do you create a reference to a DOM element in React?

Using createRef
Using useState
Using useEffect
Using useReducer

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Which of the following Hooks can be used to subscribe to document title changes in React?

useEffect
useMemo
useContext
useDocumentTitle

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What is the difference between props and state in React?

props are mutable, state is not
state is immutable, props are not
props are immutable, state is mutable
props are for functions, state is for classes

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What is the purpose of the 'getDerivedStateFromProps' method in React?

To update the component's state based on props changes
To initialize the component's state
To perform side effects after rendering
To handle component errors

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What does setState do in a class component?

Directly changes state
Merges the old and new state
Deletes the state
Calls the render method

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What is the purpose of the 'strict mode' in React?

To enforce strict syntax rules
To provide a development-friendly environment
To optimize performance
To enable additional debugging checks

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What is the purpose of the 'useMemo' Hook in React?

To memoize expensive calculations
To update the component's state
To handle component errors
To perform side effects in function components

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In React, what does the virtual DOM do?

It directly manipulates the real DOM
It optimizes CSS styling
It provides a way to manipulate browser cookies
It reconciles the changes made to the UI

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Which of the following methods is used to update the state based on the previous state in React?

this.updateState()
this.setState()
this.changeState()
this.modifyState

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In React, what is the purpose of the 'shouldComponentUpdate' method?

To determine if a component should be rendered
To define component lifecycle
To handle component events
To manage component input

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What is the purpose of render props in React?

To share logic between components
To manage state
To handle side effects
To fetch data

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What is the purpose of the 'ErrorBoundary' component in React?

To handle errors that occur during rendering
To define error messages
To catch errors in child components
To prevent errors from occurring

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What is the purpose of StrictMode in React?

To highlight potential problems
To manage state
To fetch data
To handle errors

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Which of the following statements about React Suspense is true?

It is used to handle errors in React components
It is used to suspend rendering while waiting for data to load
It is deprecated in the latest version of React
It is used to manage component state

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What is the purpose of the 'key' prop in React?

It specifies the CSS class of an element
It provides a unique identifier for a component in an array
It defines the initial state of a component
It sets the default props of a component

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What is React Router used for?

Managing state
Making API calls
Handling routing in a React application
Styling components

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What is the virtual DOM in React?

A real DOM that is virtualized
A JavaScript object
An API for backend calls
A type of database

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How do you handle forms in React?

Using Redux
Using refs
Using state
Using Context API

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What is the purpose of PropTypes in React?

To specify the type of data expected in props
To define the initial state of a component
To manage component input
To handle component events

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Which method is used to render elements to the DOM in React?

ReactDOM.render()
React.render()
ReactDOM.mount()
React.mount

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What is React.js primarily used for?

Data analysis
UI development
Database management
Machine learning

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What is the purpose of the 'key' prop in React lists?

To specify the index of each item in the list
To uniquely identify each item in the list
To provide styling information for list items
To define the initial state of list items

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How do you update state in a functional component?

Using setState
Using this.state
Using this.setState
Using useState

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