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Which of the following is NOT a way to handle events in React?

Inline event handlers
Event delegation
Event listeners
Synthetic events

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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 React.js?

A programming language
A JavaScript library for building user interfaces
A database management system
An operating systemAnswer

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What is the purpose of memo in React?

To memoize functions
To prevent unnecessary re-renders
To handle state
To fetch data

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How can you prevent a component from rendering in React?

By setting the 'visible' attribute to false
By returning null from the render method
By using the 'shouldComponentUpdate' method
By removing the component from the component tree

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What is the context API used for?

State management across components
DOM manipulation
CSS styling
Server-side rendering

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What is the purpose of ErrorBoundary in React?

To catch JavaScript errors in components
To manage state
To handle routing
To fetch data

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What is prop drilling?

Passing props to multiple components
Updating state in child components
Updating props in parent components
Passing state down multiple levels

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What is the purpose of middleware in Redux?

To handle asynchronous actions
To handle synchronous actions
To fetch data
To manage state

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How do you create a controlled component in React?

By using refs
By managing the component state
By setting the 'controlled' attribute
By using event listeners

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How do you share state between components?

Using props
Using state
Using context
Using events

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How can you optimize performance in React?

By using pure components
By minimizing the use of inline styles
By avoiding unnecessary re-renders
All of the above

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Which of the following is NOT a valid way to define a component in React?

Function Component
Class Component
Component Component
Higher-Order Component

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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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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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Which lifecycle method is invoked immediately after updating occurs in React?

componentWillUpdate()
componentDidUpdate()
componentWillMount()
componentDidMount

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How do you unmount a component in React?

Using componentWillUnmount
Using componentDidMount
Using useEffect
Using setState

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What is the purpose of prop-types library?

To type-check props
To handle state
To manage context
To fetch data

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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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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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What is the purpose of useCallback hook?

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

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Which method is called when a component is first added to the DOM?

componentDidMount()
componentWillMount()
componentWillUpdate()
componentDidUpdate

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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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What is Redux used for?

State management
Routing
CSS styling
API calls

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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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What is the purpose of keys in React?

To identify elements uniquely
To set state
To define props
To handle events

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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 the useEffect hook do?

Manages state
Fetches data
Performs side effects in components
Defines components

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What is the purpose of the 'useCallback' 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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How do you lazy load components in React?

Using React.lazy
Using useEffect
Using useContext
Using useState

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