Learn React Js MCQs
Prepare React Js MCQs (Multiple choice Questions) for exam and job interviews.
What is the purpose of `propTypes` in React?
1) To define component styles
2) To define initial state
3) To type-check props passed to components
4) To render components conditionally
Answer : Option 3
How do you manage global state in a React application?
1) Using `useEffect` hook
2) Using `React.memo`
3) Using `Context API` or state management libraries like Redux
4) Using `localStorage`
Answer : Option 3
What does `useEffect` return?
1) A cleanup function
2) An array of dependencies
3) An event listener
4) A DOM element
Answer : Option 1
How do you create a ref in React?
1) Using `useRef` hook
2) Using `useState` hook
3) Using `createRef` method
4) Using `useContext` hook
Answer : Option 1
What is the purpose of `React.StrictMode`?
1) To enable concurrent mode
2) To check for potential problems in the application
3) To improve performance
4) To handle side effects
Answer : Option 2
How do you create a context in React?
1) Using `createContext` method
2) Using `useState` hook
3) Using `useEffect` hook
4) Using `React.createClass`
Answer : Option 1
What is the purpose of `componentDidMount` lifecycle method?
1) To handle events
2) To fetch data
3) To perform actions after the component has been rendered
4) To set initial state
Answer : Option 3
How do you style components in React?
1) Using `CSS` files
2) Using `styled-components` library
3) Using `inline styles`
4) All of the above
Answer : Option 4
What does `shouldComponentUpdate` return?
1) A DOM node
2) A new state
3) A boolean value to decide whether the component should update
4) An event handler
Answer : Option 3
How do you create a higher-order component (HOC) in React?
1) Using `createElement` method
2) Using `React.memo`
3) By wrapping a component in another component
4) Using `useEffect` hook
Answer : Option 3