What is the primary purpose of error boundaries in React?
- To catch and handle errors gracefully.
- To display an error message to users.
- To prevent all errors from occurring.
- To speed up the rendering process.
Error boundaries in React are primarily used to catch and handle errors gracefully, preventing them from crashing the entire application. When an error occurs within the boundary of an error boundary component, React can display a fallback UI or perform other actions to ensure a smoother user experience. They don't prevent all errors but provide a way to manage them more gracefully.
When optimizing a React application using Websockets for real-time financial data, the pattern where only data changes (deltas) are sent instead of the full dataset is known as ________.
- Data Streaming
- Data Syncing
- Delta Streaming
- Event Broadcasting
The pattern where only data changes (deltas) are sent instead of the full dataset is known as "Delta Streaming." In real-time financial data scenarios, sending only the changes in data helps optimize bandwidth usage and improve the overall performance of the application. It reduces the amount of data transmitted and processed, making it a common practice in real-time applications.
You notice that a React component handling real-time chat messages re-renders excessively, even when no new messages are received. What could be a probable cause, and how would you address it?
- The component is not using PureComponent or memoization.
- There is a memory leak in the component.
- The chat messages are not being received correctly.
- The server is not sending updates efficiently.
Excessive re-renders in a React component can often be caused by not using PureComponent or memoization. PureComponent and memoization techniques help prevent unnecessary re-renders when no new data has arrived, optimizing performance. Addressing this issue involves implementing PureComponent or memoization in the component to reduce unnecessary rendering. The other options do not directly address the probable cause.
When using React.lazy(), it's recommended to handle network failures using a component that wraps around ________.
- ErrorBoundary
- ErrorWrapper
- FallbackComponent
- Suspense
When using React's React.lazy() for code splitting and dynamic imports, it's recommended to handle network failures by wrapping your lazy-loaded components with an ErrorBoundary. The ErrorBoundary component catches any errors that occur during the loading of the lazy component and allows you to display a fallback UI or handle the error gracefully.
To create a cross-platform mobile application using React's principles, developers often turn to ________.
- Angular
- React Native
- Vue.js
- Xamarin
To create a cross-platform mobile application using React's principles, developers often turn to React Native. React Native is a framework that allows developers to build mobile applications for iOS and Android using React's component-based approach. Angular, Vue.js, and Xamarin are alternatives to React Native for cross-platform mobile development, but they are not specifically built on React's principles.
In MobX, what is the best practice for modifying observable state?
- Directly modifying the state without any restrictions.
- Modifying the state only within actions or reactions.
- Only allowing modifications in the constructor of the class.
- Using third-party libraries for state management.
The best practice in MobX is to modify observable state only within actions or reactions. This ensures that state changes are tracked correctly and that MobX can optimize reactivity. Directly modifying the state without restrictions can lead to unpredictable behavior. The other options are not considered best practices in MobX.
In Next.js, how would you run code exclusively on the server and not expose it to the client-side bundle?
- Include the code in the main JavaScript bundle.
- Place the code in the client/ directory.
- Use a