Learn React Js MCQs
Prepare React Js MCQs (Multiple choice Questions) for exam and job interviews.
What does the `useState` hook return?
1) A value and a setter function
2) A state variable and a ref
3) A state variable and a callback function
4) A prop and a function
Answer : Option 1
How do you perform routing in React?
1) Using `useState` hook
2) Using `React Router` library
3) Using `window.location`
4) Using `fetch` API
Answer : Option 2
What is the purpose of `useContext` hook?
1) To manage component state
2) To handle side effects
3) To consume context in functional components
4) To create a new context
Answer : Option 3
How do you make an API call in React?
1) Using `window.fetch`
2) Using `XMLHttpRequest`
3) Using `useEffect` with fetch or axios
4) Using `window.location`
Answer : Option 3
What is the significance of the `defaultValue` prop in React?
1) To set the initial value of a controlled input
2) To set the initial value of an uncontrolled input
3) To create a default state
4) To set default props
Answer : Option 2
How do you optimize performance in React?
1) Using `componentWillMount`
2) Using `componentDidMount`
3) Using `React.memo` or `useMemo`
4) Using `shouldComponentUpdate`
Answer : Option 3
What is the purpose of `useReducer` hook?
1) To handle side effects
2) To manage complex state logic
3) To fetch data from an API
4) To manage component lifecycle
Answer : Option 2
How do you create a class component in React?
1) Using `React.createClass`
2) Using `function` keyword
3) Using `class` keyword
4) Using `React.Component`
Answer : Option 3
What does the `ReactDOM.render` method do?
1) Renders a React element into a DOM node
2) Creates a virtual DOM
3) Returns a JSX element
4) Adds a component to the component tree
Answer : Option 1
How do you handle errors in React components?
1) Using `try-catch` blocks
2) Using `componentDidCatch` lifecycle method or `ErrorBoundary`
3) Using `useEffect` hook
4) Using `componentDidMount`
Answer : Option 2