React JS MCQs with answers Page - 21

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. How do you access props in a functional React component?

  • (A) Using this.props
  • (B) Passing props as function arguments
  • (C) Using state
  • (D) Using context

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Q. What is a higher-order component (HOC) in React?

  • (A) A component that returns another component
  • (B) A component that is used to wrap multiple components
  • (C) A function that takes a component and returns a new component
  • (D) A component with higher z-index

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Q. Which React hook is used to access the context value?

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

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Q. What does the 'useRef' hook do?

  • (A) Keeps a mutable reference that persists across renders
  • (B) Manages state in functional components
  • (C) Runs side effects after rendering
  • (D) Memoizes a function

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Q. What is the default behavior of setState in class components?

  • (A) It merges the new state with the existing state
  • (B) It replaces the entire state object
  • (C) It immediately updates the state synchronously
  • (D) It triggers a full page reload

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Q. What is the significance of keys when rendering lists in React?

  • (A) They help React identify which items changed, added, or removed
  • (B) They add accessibility features
  • (C) They are used to style list items
  • (D) They bind events to list items

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Q. Which method is used to convert JSX to React elements?

  • (A) React.createElement
  • (B) React.convertJSX
  • (C) JSX.parse
  • (D) React.renderJSX

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Q. How can you memoize a React component to avoid unnecessary re-renders?

  • (A) Using React.memo
  • (B) Using useState
  • (C) Using setState
  • (D) Using useEffect

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Q. What is the correct way to handle events in React?

  • (A) Use camelCase event handlers, e.g., onClick
  • (B) Use lowercase event handlers, e.g., onclick
  • (C) Attach events directly to DOM elements using addEventListener
  • (D) Events cannot be handled in React

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Q. Which hook should you use to access the previous state value?

  • (A) useRef
  • (B) usePrevious (custom hook)
  • (C) useState
  • (D) useEffect

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