In a project, you have a theme toggle button that switches between dark and light modes. Nested deeply within the component hierarchy is a button that needs to know the current theme. How can you efficiently provide the theme information to the button without prop drilling?
- Pass the theme information as a URL parameter using React Router.
- Use React's useContext hook to access the theme information from a context provider higher in the component tree.
- Use a global JavaScript variable to store and access the current theme.
- Use a third-party state management library like Mobx or Recoil to share the theme information across components.
To efficiently provide the theme information to a deeply nested button without prop drilling, you can use React's useContext hook. This hook allows you to access the theme information from a context provider higher in the component tree without passing it down as props. Using third-party libraries or URL parameters is not the most straightforward and efficient approach, and using a global JavaScript variable can lead to issues with component re-renders and isn't recommended.
In large state trees, the principle that allows unchanged parts of the old state and the new state to point to the same memory locations is called ________.
- Garbage Collection
- Memory Reuse
- Referential Equality
- Structural Sharing
In large state trees, the principle that allows unchanged parts of the old state and the new state to point to the same memory locations is called Structural Sharing. This technique is essential in state management libraries like Redux to optimize memory usage and enhance performance when updating state. It doesn't involve garbage collection, memory reuse in the same sense, or referential equality as the primary goal.
When a Websocket connection is closed unexpectedly, the Websocket object emits a ________ event.
- close
- disconnect
- error
- terminate
When a WebSocket connection is closed unexpectedly, the WebSocket object emits an error event. This event is crucial for handling unexpected disconnections and potential issues in your WebSocket communication. Developers can listen for this event and implement error-handling logic as needed.
What is the primary purpose of using GraphQL with React?
- To create responsive, mobile-friendly designs.
- To efficiently fetch and manage data from a server.
- To manage state in React components.
- To style React components.
The primary purpose of using GraphQL with React is to efficiently fetch and manage data from a server. GraphQL allows you to request only the data you need, reducing over-fetching and under-fetching of data, which can be common in RESTful APIs. While React manages state and rendering, GraphQL focuses on data retrieval and manipulation.
In the context of GraphQL, what does Apollo Client help with?
- Querying and managing data from a GraphQL server.
- Running unit tests in React.
- State management in React applications.
- Styling React components.
Apollo Client is primarily used in the context of GraphQL to query and manage data from a GraphQL server. It simplifies data fetching, caching, and state management for GraphQL queries and mutations in React applications. It is not related to styling or unit testing React components, which are different concerns.
How can TypeScript enhance the development experience in a large-scale React project?
- By providing advanced features for state management.
- By adding support for complex CSS animations.
- By enabling real-time collaboration with designers.
- By optimizing server-side rendering.
TypeScript enhances the development experience in large-scale React projects by providing advanced features for type checking, which catch errors at compile time and improve code quality. This helps prevent runtime issues, especially in complex applications. While other options may be valuable in a React project, they are not the primary ways TypeScript enhances development in this context.
In terms of performance optimization, what concern might you have when using CSS-in-JS libraries extensively?
- Increased JavaScript bundle size.
- Reduced modularity and maintainability.
- Slower rendering due to server-side processing.
- Incompatibility with modern browsers.
When using CSS-in-JS libraries extensively, one concern is the increased JavaScript bundle size. These libraries often generate JavaScript code to handle styles, which can bloat the bundle size. This can impact website performance, especially on slower networks. The other options do not accurately represent the primary performance concern associated with CSS-in-JS libraries.
How does the use of Immutable.js impact the performance of a React application compared to using native JavaScript objects?
- Degrades performance due to increased memory consumption.
- Enhances performance but makes code more complex.
- Has no impact on performance but simplifies code.
- Improves performance significantly by reducing memory consumption.
Immutable.js can significantly improve the performance of a React application by reducing memory consumption. This is because Immutable.js employs structural sharing, allowing efficient updates without copying all data. While it may add some complexity to the code, it's a trade-off for improved performance. Using native JavaScript objects typically involves more copying and can lead to increased memory usage.
What potential issues might arise if event handlers are not properly bound in class components?
- Components may fail to render.
- Event handlers may execute too slowly.
- Event handlers will have higher priority.
- Memory leaks may occur.
If event handlers are not properly bound in class components, memory leaks can occur. This happens because the event handlers may retain references to component instances, preventing them from being garbage collected. It can lead to performance issues and potential memory exhaustion. Correctly binding event handlers is essential for avoiding these issues.
In MobX, which decorator is used to mark a property as observable?
- @component
- @observable
- @state
- @watch
In MobX, the @observable decorator is used to mark a property as observable. When a property is marked as observable, MobX can track changes to it and automatically update any components that depend on it when it changes. This is a key feature for reactive state management in MobX.
In React Native, instead of using HTML's , you would use ________.
In React Native, instead of using HTML's
, you would use the component. The component is a fundamental building block for creating layouts and structuring content in React Native applications. It is used to group and style elements much like
in HTML. , , and are not standard React Native components.
To transform an Immutable.js List into a native JavaScript array, you would use the method ________.
- convertToArray()
- listToArray()
- toArray()
- toNativeArray()
To transform an Immutable.js List into a native JavaScript array, you would use the method toArray(). This method is used to convert an Immutable.js List into a plain JavaScript array, making it easier to work with native JavaScript functions.
In React Native, instead of using HTML's
, you would use the component. The component is a fundamental building block for creating layouts and structuring content in React Native applications. It is used to group and style elements much like
in HTML. , , and are not standard React Native components.
To transform an Immutable.js List into a native JavaScript array, you would use the method ________.
- convertToArray()
- listToArray()
- toArray()
- toNativeArray()
To transform an Immutable.js List into a native JavaScript array, you would use the method toArray(). This method is used to convert an Immutable.js List into a plain JavaScript array, making it easier to work with native JavaScript functions.