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.
Which popular React framework is primarily used for Server-Side Rendering?
- Angular
- Next.js
- Redux
- Vue.js
Next.js is a popular React framework primarily used for Server-Side Rendering (SSR). It simplifies the process of building SSR-enabled React applications, providing features like automatic code splitting and routing. While Redux is a state management library for React, Angular is a different framework, and Vue.js is another JavaScript framework, they are not primarily used for SSR in the same way Next.js is.
How do CSS-in-JS libraries like styled-components handle server-side rendering (SSR) for styling?
- They do not support SSR.
- They generate inline styles on the server-side.
- They rely on external CSS files for SSR.
- They dynamically load styles on the client-side after rendering.
CSS-in-JS libraries like styled-components generate inline styles on the server-side, which are then included in the HTML response. This approach ensures that styles are applied during the initial render on the server, enhancing performance and SEO. The other options do not accurately describe how CSS-in-JS libraries handle SSR.
In React, ______ and Suspense are used together to implement lazy loading of components.
- React.lazy()
- useEffect() and Fetch
- useState() and Axios
- useMemo() and Promises
In React, React.lazy() and Suspense are used together to implement lazy loading of components. React.lazy() allows you to dynamically load a component when it's needed, and Suspense is used to handle loading states. The other options are not directly related to lazy loading components.
Which hook would be best suited to manage the global state of an application?
- useContext
- useEffect
- useRef
- useState
The hook best suited to manage the global state of an application is useContext. useContext provides a way to share data (state) between components without prop drilling. It is often used in combination with useReducer or useState to manage global application state. While the other hooks have their use cases, useContext is specifically designed for global state management in React applications.
The Context API provides a way to pass data through the component tree without having to pass props down manually at every level using the ________ and ________ mechanism.
- Provider and Consumer
- State and Props
- Render Props and HOC
- Redux and MobX
The Context API in React provides the Provider and Consumer components, which allow data to be passed through the component tree without the need to manually pass props down at every level. This mechanism simplifies state management in complex React applications. While the other options are related to React state management, they do not specifically describe the Context API mechanism.
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.