React JS MCQs with answers Page - 1

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 purpose of the useState hook in React?

  • (A) To perform side effects
  • (B) To manage component state
  • (C) To fetch data from API
  • (D) To navigate between pages

A

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Q. Which method is used to render React components to the DOM?

  • (A) React.render()
  • (B) ReactDOM.render()
  • (C) renderComponent()
  • (D) Component.render()

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Q. In React, what is JSX?

  • (A) A templating engine
  • (B) A type of CSS
  • (C) JavaScript XML syntax for defining UI
  • (D) A server-side scripting language

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Q. Which hook is used to perform side effects in functional components?

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

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Q. What is the virtual DOM in React?

  • (A) A real DOM in memory
  • (B) A UI rendered in JavaScript
  • (C) A lightweight in-memory representation of the real DOM
  • (D) A CSS engine

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Q. What is the default state of a new useState variable?

Code: 
const [count, setCount] = useState();
  • (A) 0
  • (B) undefined
  • (C) null
  • (D) 1

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Q. Which method is used to pass data from parent to child in React?

  • (A) props
  • (B) state
  • (C) context
  • (D) dispatch

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

  • (A) By returning null in render
  • (B) By using React.memo
  • (C) By avoiding JSX
  • (D) By not using useState

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Q. What does the key prop do in React lists?

  • (A) It sets the list style
  • (B) It uniquely identifies elements for efficient updates
  • (C) It adds a password to components
  • (D) It defines accessibility

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Q. Which hook allows sharing logic between components in React?

  • (A) useCallback
  • (B) useState
  • (C) Custom hooks
  • (D) useEffect

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