250+ React Js MCQ With Online Practice Test

React.js, often simply called React, is a highly popular JavaScript library for building user interfaces. Developed and maintained by Facebook, React is renowned for its component-based architecture and the ability to efficiently update and render components when data changes. It is a foundational tool for developing modern web and mobile applications, allowing developers to create dynamic and interactive user interfaces with ease. React's vast ecosystem, including tools like React Native for mobile app development, makes it a top choice for frontend development and a key player in the world of web technologies.

Practice Test

151. In React, what is an error boundary?

Answer: A higher-order component that catches errors

152. How do you define an error boundary in React?

Answer: By wrapping a component with <ErrorBoundary>

153. When does an error boundary catch errors in React?

Answer: In both development and production environments

154. In React, what is the purpose of the componentDidCatch lifecycle method?

Answer: To handle errors and display a fallback UI

155. What happens if an error boundary fails to catch an error in React?

Answer: The application crashes

156. How can you nest error boundaries in a React application?

Answer: By wrapping error boundaries around components

157. In React, what is the purpose of the getDerivedStateFromError lifecycle method in error boundaries?

Answer: To handle errors and update component state

158. Which of the following is a common approach for handling errors in React?

Answer: Displaying an error message to the user

159. What is one of the benefits of using error boundaries in React?

Answer: Improved debugging and error isolation

160. In React, what should you do if an error boundary catches an error that it cannot handle?

Answer: Rethrow the error to the parent error boundary
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React Js Multiple Choice Questions React Js MCQ React Js Interview Questions With Answers