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.
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Practice Test
151. In React, what is an error boundary?
A. A higher-order component that catches errors
B. A React component that renders errors
C. A built-in JavaScript error handler
D. A type of event listener
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Answer: A higher-order component that catches errors
152. How do you define an error boundary in React?
A. By using the errorBoundary attribute
B. By wrapping a component with <ErrorBoundary>
C. By using the catchError method
D. By adding an onError event handler
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Answer: By wrapping a component with <ErrorBoundary>
153. When does an error boundary catch errors in React?
A. During component rendering
B. In the development environment only
C. In the production environment only
D. In both development and production environments
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Answer: In both development and production environments
154. In React, what is the purpose of the componentDidCatch lifecycle method?
A. To log errors to the console
B. To handle errors and display a fallback UI
C. To trigger a re-render of the component
D. To prevent errors from occurring
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Answer: To handle errors and display a fallback UI
155. What happens if an error boundary fails to catch an error in React?
A. The error is logged to the console
B. The application crashes
C. The error is passed to the parent error boundary
D. The error is silently ignored
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Answer: The application crashes
156. How can you nest error boundaries in a React application?
A. By using the try-catch statement
B. By wrapping error boundaries around components
C. By using the catch prop in components
D. By creating separate error boundary components
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Answer: By wrapping error boundaries around components
157. In React, what is the purpose of the getDerivedStateFromError lifecycle method in error boundaries?
A. To log errors to the console
B. To handle errors and update component state
C. To trigger a re-render of the component
D. To prevent errors from occurring
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Answer: To handle errors and update component state
158. Which of the following is a common approach for handling errors in React?
A. Using console.error to log errors
B. Displaying an error message to the user
C. Redirecting the user to a different page
D. Silently ignoring errors
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Answer: Displaying an error message to the user
159. What is one of the benefits of using error boundaries in React?
A. Improved debugging and error isolation
B. Faster component rendering
C. Increased application speed
D. Reduced code complexity
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Answer: Improved debugging and error isolation
160. In React, what should you do if an error boundary catches an error that it cannot handle?
A. Log the error and display a friendly message
B. Rethrow the error to the parent error boundary
C. Ignore the error and continue rendering
D. Restart the entire application
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Answer: Rethrow the error to the parent error boundary
