Learn React Js MCQs
Prepare React Js MCQs (Multiple choice Questions) for exam and job interviews.
How do you prevent re-renders in a React component?
1) Using `useState`
2) Using `React.memo`
3) Using `useEffect`
4) Using `useReducer`
Answer : Option 2
What is the purpose of `useEffect`?
1) To manage state
2) To handle side effects in a component
3) To create refs
4) To optimize performance
Answer : Option 2
How do you optimize performance in a React application?
1) Using `useState`
2) Using `useMemo` and `React.memo`
3) Using `useEffect`
4) Using `useReducer`
Answer : Option 2
What is the purpose of `React.Portal`?
1) To manage state
2) To render children into a DOM node that exists outside the DOM hierarchy of the parent component
3) To create refs
4) To handle side effects
Answer : Option 2
How do you create higher-order components in React?
1) By wrapping a component with another function
2) Using `useState`
3) Using `useEffect`
4) Using `React.forwardRef`
Answer : Option 1
What is the purpose of `React.Suspense`?
1) To manage state
2) To handle asynchronous rendering of components
3) To create refs
4) To handle side effects
Answer : Option 2
How do you handle complex state logic in React?
1) Using `useState`
2) Using `useEffect`
3) Using `useReducer`
4) Using `useRef`
Answer : Option 3
What is the purpose of `useCallback` in React?
1) To manage state
2) To handle side effects
3) To memoize a callback function
4) To create refs
Answer : Option 3
How do you handle user authentication in a React app?
1) Using `useState`
2) Using `useContext` and `context` API
3) Using `useEffect`
4) Using `useRef`
Answer : Option 2
What is the purpose of the `useReducer` hook?
1) To manage state that depends on previous state
2) To create refs
3) To handle side effects
4) To optimize performance
Answer : Option 1