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React JS MCQs 11
- 101. In React, which lifecycle method is called when a component is about to update?
- a) componentWillMount
- b) componentDidUpdate
- c) componentWillUpdate (Correct Answer)
- d) componentDidMount
- 102. How do you access route parameters in a React component using React Router?
- a) By using the `this.params` object
- b) By using the `this.props.params` object
- c) By using the `useParams()` hook (Correct Answer)
- d) By accessing the `params` object directly from the router
- 103. What is the purpose of the `Fragment` component in React?
- a) To create a new component
- b) To group multiple elements without adding extra nodes to the DOM (Correct Answer)
- c) To provide default props to a component
- d) To define global styles for the entire application
- 104. How do you prevent a component from re-rendering unnecessarily in React?
- a) By using the `shouldComponentUpdate` method in class components
- b) By using the `React.memo` higher-order component for functional components
- c) By using the `PureComponent` class in class components
- d) All of the above (Correct Answer)
- 105. What does the `dangerouslySetInnerHTML` attribute do in React?
- a) It allows you to define HTML attributes with dynamic values
- b) It sets the inner HTML of a React element from a string (Correct Answer)
- c) It allows you to define inline styles with dynamic values
- d) It prevents XSS attacks in React components
- 106. How do you conditionally apply styles to a React component?
- a) By using the `style` attribute with an object containing conditional styles
- b) By using the `className` attribute with conditional CSS classes
- c) By using CSS-in-JS libraries like styled-components
- d) All of the above (Correct Answer)
- 107. What is the purpose of the `forwardRef` function in React?
- a) To forward props from parent to child components
- b) To forward DOM attributes from parent to child components
- c) To forward refs from parent to child components (Correct Answer)
- d) To forward context from parent to child components
- 108. How do you perform code splitting in React?
- a) By using dynamic imports with `React.lazy` and `Suspense`
- b) By splitting the code manually into smaller chunks
- c) By using the `SplitChunksPlugin` in Webpack
- d) All of the above (Correct Answer)
- 109. What is the purpose of the `useReducer` hook in React?
- a) To manage component state
- b) To manage complex state logic and perform state transitions (Correct Answer)
- c) To create reusable custom hooks
- d) To fetch data from an API
- 110. How do you handle errors in React components?
- a) By using the `try-catch` statement inside the `render` method
- b) By using the `componentDidCatch` lifecycle method (Correct Answer)
- c) By using the `ErrorBoundary` component provided by React
- d) All of the above
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