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.
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.
For improved performance in React Native, what can you use to run computationally heavy operations off the main UI thread?
- JavaScript timers (setTimeout and setInterval).
- Promises and async/await functions.
- Redux for managing state asynchronously.
- Web Workers and the "react-native-webview" library.
To enhance performance in React Native and prevent the main UI thread from becoming unresponsive during computationally heavy tasks, you can use Web Workers and the "react-native-webview" library. Web Workers allow you to run JavaScript code in a separate background thread, keeping the UI responsive. "react-native-webview" provides a WebView component with Web Worker support, making it a suitable choice for offloading heavy computations. JavaScript timers, Promises, and Redux are not primarily designed for offloading heavy computations.
You are building a feature where you have to compare the current state and the next state of a component to decide whether it should re-render. How can Immutable.js assist in this comparison?
- Immutable.js allows you to directly modify the component's state without re-rendering.
- Immutable.js is not suitable for this purpose.
- Immutable.js provides a built-in function called shouldComponentUpdate that automatically handles state comparison.
- You must use a third-party library for this comparison.
Immutable.js provides a built-in function called shouldComponentUpdate that allows you to easily compare the current state with the next state to determine whether a component should re-render. This function helps optimize rendering performance by avoiding unnecessary re-renders when the state has not changed.
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.
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.