Learn React Js MCQs
Prepare React Js MCQs (Multiple choice Questions) for exam and job interviews.
How do you memoize a callback function in React?
1) Using `useMemo`
2) Using `useEffect`
3) Using `useCallback`
4) Using `useState`
Answer : Option 3
How do you access a component’s state in a class component?
1) Using `this.state`
2) Using `this.props`
3) Using `this.context`
4) Using `this.ref`
Answer : Option 1
What is the purpose of the `key` prop in React?
1) To identify unique elements in a list
2) To manage state
3) To handle side effects
4) To optimize rendering
Answer : Option 1
How do you set default props in a functional component?
1) Using the `useState` hook
2) Using the `defaultProps` property
3) Using default function parameters
4) Using `useEffect`
Answer : Option 3
What is the purpose of the `React.memo` function?
1) To handle side effects
2) To optimize rendering by memoizing a component
3) To create refs
4) To manage state
Answer : Option 2
How do you pass data from child to parent in React?
1) Using `props`
2) Using `context`
3) Using a callback function
4) Using `useState`
Answer : Option 3
What is the purpose of the `useImperativeHandle` hook?
1) To manage state
2) To create refs
3) To customize the instance value that is exposed to parent components when using refs
4) To handle side effects
Answer : Option 3
How do you handle side effects in a functional component?
1) Using `useState`
2) Using `useEffect`
3) Using `useReducer`
4) Using `useRef`
Answer : Option 2
What is the purpose of `React.PureComponent`?
1) To manage state
2) To handle side effects
3) To optimize performance by preventing unnecessary re-renders
4) To create refs
Answer : Option 3
How do you access a DOM element in a functional component?
1) Using `useRef`
2) Using `useState`
3) Using `useEffect`
4) Using `useContext`
Answer : Option 1