React JS MCQs 6

In React, which method is called before the component is removed from the DOM?

• a) componentWillUnmount (Correct Answer)
• b) componentDidMount
• c) componentDidUpdate
• d) componentWillMount

What is the purpose of the useContext hook in React?

• a) To manage component state
• b) To handle context within class components
• c) To access context values in functional components (Correct Answer)
• d) To fetch data from an external API

Which of the following is a valid way to define a React functional component?

• a) function MyComponent() {}
• b) const MyComponent = () => {}
• c) class MyComponent extends React.Component {}
• d) All of the above (Correct Answer)

What is the primary role of ReactDOM in a React application?

• a) To handle routing and navigation
• b) To manage global application state
• c) To render React components into the DOM (Correct Answer)
• d) To handle server-side rendering

What is the purpose of the useMemo hook in React?

• a) To memoize the result of a function so that it is only recomputed when its dependencies change (Correct Answer)
• b) To perform side effects in functional components
• c) To manage component state
• d) To subscribe to context changes

In React, what does it mean to lift state up?

• a) It refers to managing state at the lowest level of the component tree
• b) It refers to passing state from child to parent components
• c) It refers to moving state to a common ancestor component to share it between sibling components (Correct Answer)
• d) It refers to removing state from a component

What is the purpose of the defaultProps property in a React component?

• a) To define default values for props (Correct Answer)
• b) To set the initial state of a component
• c) To define the default styling for a component
• d) To handle default event behavior

In React, what is the purpose of the key prop when rendering a list of components?

• a) It defines the style of each list item
• b) It helps React identify which items have changed, are added, or are removed in the list (Correct Answer)
• c) It sets the initial state of each list item
• d) It specifies the order of the list items

What is the purpose of the children prop in a React component?

• a) It represents the child components rendered inside the component (Correct Answer)
• b) It defines the default content of the component
• c) It passes data from parent to child components
• d) It defines the structure of the component

Which of the following statements about React components is true?

• a) Functional components can have lifecycle methods
• b) Class components can return multiple elements without using a wrapper element
• c) Functional components are simpler and easier to read and write compared to class components (Correct Answer)
• d) All of the above