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.
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.
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.
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.
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.
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.