React JS MCQs with answers Page - 6

Here, you will find a collection of MCQ questions on React JS. Go through these questions to enhance your preparation for upcoming examinations and interviews.

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Q. What is the main purpose of useEffect in React?

  • (A) To update props
  • (B) To perform side effects
  • (C) To create components
  • (D) To render JSX

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Q. Which of the following will NOT cause a component to re-render?

  • (A) State change
  • (B) Prop change
  • (C) Context change
  • (D) Local variable change

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Q. Which hook allows you to access the DOM element directly?

  • (A) useEffect
  • (B) useMemo
  • (C) useRef
  • (D) useState

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Q. Which lifecycle method is equivalent to useEffect with an empty dependency array?

  • (A) componentDidMount
  • (B) componentDidUpdate
  • (C) componentWillUnmount
  • (D) shouldComponentUpdate

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Q. In JSX, how do you write a JavaScript expression?

  • (A) With double quotes
  • (B) With parentheses
  • (C) With square brackets
  • (D) With curly braces

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Q. Which of these is not a valid React event?

  • (A) onClick
  • (B) onSubmit
  • (C) onHover
  • (D) onChange

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Q. What will happen if you modify state directly in React?

  • (A) Component re-renders correctly
  • (B) State change is ignored
  • (C) React throws an error
  • (D) Component may behave unexpectedly

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Q. What is the output of React.createElement?

  • (A) HTML element
  • (B) JSX code
  • (C) React element
  • (D) DOM node

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Q. What does a React component return?

  • (A) String
  • (B) Object
  • (C) JSX
  • (D) HTML

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Q. Which command is used to start a React app in development mode?

  • (A) npm start
  • (B) npm build
  • (C) npm install
  • (D) npm test

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