Learn React Js MCQs
Prepare React Js MCQs (Multiple choice Questions) for exam and job interviews.
What is the purpose of `useCallback` hook?
1) To manage side effects
2) To memoize functions and prevent unnecessary re-renders
3) To manage state
4) To create refs
Answer : Option 2
How do you add event listeners in React?
1) Using `addEventListener`
2) Using `document.getElementById`
3) Using `on
4) Using `window.addEventListener`
Answer : Option 3
What is the purpose of `React.memo`?
1) To manage component state
2) To create a class component
3) To optimize performance by memoizing functional components
4) To create refs
Answer : Option 3
How do you perform side effects in a React function component?
1) Using `useState` hook
2) Using `useMemo` hook
3) Using `useEffect` hook
4) Using `useRef` hook
Answer : Option 3
What does `useState` hook accept as an argument?
1) A function
2) A number
3) An initial state value
4) A boolean
Answer : Option 3
How do you update the state in a React class component?
1) Using `setState` method
2) Using `useState` hook
3) Using `forceUpdate` method
4) Using `updateState` method
Answer : Option 1
What is the purpose of `React.Children` utility?
1) To create new child components
2) To clone child elements
3) To work with and manipulate the children passed to a component
4) To manage state
Answer : Option 3
How do you access props in a React functional component?
1) Using `this.props`
2) Using `useEffect` hook
3) Using `props` argument
4) Using `useState` hook
Answer : Option 3
What is the purpose of `defaultProps` in React?
1) To set default values for props
2) To define prop types
3) To manage state
4) To handle side effects
Answer : Option 1
How do you pass data between sibling components in React?
1) Using state
2) Using refs
3) By lifting state up to a common parent
4) Using context
Answer : Option 3