React JS MCQs with answers Page - 16

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. Which of the following is true about JSX?

  • (A) It is a templating engine
  • (B) It allows HTML to be written in JavaScript
  • (C) It only works in Node.js
  • (D) It cannot use JavaScript expressions

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Q. What is the default behavior of a form submission in React?

  • (A) It does nothing
  • (B) It reloads the page
  • (C) It sends an HTTP request
  • (D) It shows an alert

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Q. What is the benefit of using `React.Fragment`?

  • (A) It allows multiple return values from a function
  • (B) It reduces the size of the DOM by not adding extra nodes
  • (C) It is used for styling
  • (D) It provides lifecycle methods

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Q. What is the role of the `key` prop in React?

  • (A) To pass data to components
  • (B) To keep elements stable during updates
  • (C) To identify the component
  • (D) To trigger a rerender

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Q. Which hook would you use to share logic across multiple components?

  • (A) useEffect
  • (B) useReducer
  • (C) Custom Hook
  • (D) useRef

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Q. How is `props.children` used in React?

  • (A) To access children passed between component tags
  • (B) To access child elements in DOM
  • (C) To define default props
  • (D) To update state

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Q. Which of these is NOT true about React?

  • (A) React is a framework
  • (B) React uses a virtual DOM
  • (C) React is component-based
  • (D) React supports server-side rendering

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Q. How do you prevent a component from re-rendering?

  • (A) Using shouldComponentUpdate in class components
  • (B) Using useEffect with empty dependencies
  • (C) Using React.memo for functional components
  • (D) All of the above

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Q. What does `ReactDOM.hydrate` do?

  • (A) Mounts a React component
  • (B) Hydrates a server-rendered container
  • (C) Updates state
  • (D) Initializes a ref

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Q. What is `React.memo` used for?

  • (A) To render a component once only
  • (B) To memoize a component
  • (C) To store previous props
  • (D) To create hooks

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