If you want to apply some global styles in a Next.js app, you should modify the ________ component.
- _app.js
- _document.js
- _layout.js
- _style.js
In Next.js, if you want to apply some global styles or layout to your entire application, you should modify the _app.js component. This component is a wrapper around your entire application and allows you to include global styles and layout elements that persist across all pages. The other options are not typically used for applying global styles.
React's synthetic event system is implemented to ensure consistent behavior across different ________.
- Browsers
- Event types
- JavaScript environments
- React components
React's synthetic event system is implemented to ensure consistent behavior across different browsers. It abstracts the differences in how various browsers handle events, providing a unified and predictable interface for event handling in React applications. This helps developers write code that works consistently across different browser environments.
In React, what are synthetic events?
- Events created by React to wrap native browser events.
- Events generated by native DOM elements.
- Events that occur spontaneously in React.
- Events triggered by user actions in the browser.
In React, synthetic events are events created by React to wrap native browser events. They provide a consistent interface for handling events across different browsers. React's synthetic events are used to improve performance and ensure event handling works consistently in React components, abstracting away the differences between browsers.
In Redux, the function that specifies how the state is transformed by actions is called ________.
- Action Creator Function
- Dispatcher Function
- Reducer Function
- State Modifier Function
In Redux, the function that specifies how the state is transformed by actions is called the "Reducer Function." Reducers take the current state and an action as input and return the new state based on that action. They are a crucial part of the Redux architecture for managing state changes in a predictable and consistent manner.
The method that provides detailed information about the error and the component stack where it happened is called ________.
- renderError
- componentErrorBoundary
- errorStack
- componentStack
The method that provides detailed information about the error and the component stack where it happened is called componentStack. This information is invaluable when debugging errors in React applications as it helps developers pinpoint the exact location and context of the error. The other options (renderError, componentErrorBoundary, and errorStack) are not standard methods in React for providing this specific information.
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.
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.
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 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.
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.
Which popular library is often used in conjunction with React for managing Websocket connections?
- Axios.
- React Router.
- Redux.
- Socket.io.
Socket.io is a popular library used in conjunction with React for managing Websocket connections. Socket.io simplifies real-time communication by providing a WebSocket API that works seamlessly with React applications. Redux, React Router, and Axios are important libraries, but they are not specifically designed for Websockets; they serve other purposes, such as state management, routing, and HTTP requests, respectively.
What is the primary role of Error Boundaries in React applications?
- To handle network requests in components.
- To prevent all errors from being displayed.
- To catch and handle errors in the component tree.
- To provide styling to components in case of errors.
Error Boundaries in React applications primarily serve to catch and handle errors that occur within the component tree, preventing the entire application from crashing due to a single error. They allow you to gracefully handle errors by rendering an alternative UI or displaying an error message. The other options do not accurately describe the primary role of Error Boundaries.