Learn React Js MCQs
Prepare React Js MCQs (Multiple choice Questions) for exam and job interviews.
How do you handle asynchronous operations in React?
1) Using `useEffect` or async functions
2) By using local state
3) By using `refs`
4) By creating global variables
Answer : Option 1
What does `useEffect` hook do?
1) It performs side effects in function components
2) It creates state
3) It defines a component
4) It manages props
Answer : Option 1
How do you prevent a component from re-rendering?
1) Using `React.memo`
2) By using `useEffect`
3) By using `setState`
4) By using props
Answer : Option 1
What is the main purpose of `React Router`?
1) To manage navigation in single-page applications
2) To handle state management
3) To optimize performance
4) To create class components
Answer : Option 1
What is the purpose of the `useReducer` hook?
1) To manage complex state logic
2) To create a component
3) To handle side effects
4) To create refs
Answer : Option 1
What does the `props.children` contain?
1) The nested elements of a component
2) The props passed to the component
3) The component’s state
4) The refs of the component
Answer : Option 1
How do you handle forms in React?
1) By using controlled components
2) By using uncontrolled components
3) By using state
4) By using refs
Answer : Option 1
What does `ReactDOM.render` do?
1) Renders React elements into the DOM
2) Manages state
3) Handles side effects
4) Creates refs
Answer : Option 1
How can you optimize performance in React applications?
1) By using `React.memo`, `useMemo`, and `useCallback`
2) By using class components only
3) By avoiding functional components
4) By using global variables
Answer : Option 1
What does `useRef` do?
1) Creates a mutable object which persists for the full lifetime of the component
2) Manages state
3) Handles side effects
4) Creates a context
Answer : Option 1