To mock a resolved value of a Promise using Jest, you can use the method ________.
- mockResolvedValue
- resolveMock
- promiseValue
- mockPromise
In Jest, to mock a resolved value of a Promise, you can use the mockResolvedValue method. This allows you to specify the value that the Promise should resolve with in your test. The other options are not the correct methods for achieving this specific behavior with Promises in Jest.
How can the combination of Context API and Hooks provide state management solutions comparable to libraries like Redux?
- By allowing for centralized state management.
- By eliminating the need for any additional state management libraries.
- By integrating third-party state management tools.
- By providing advanced server-side rendering.
The combination of Context API and Hooks can provide state management solutions comparable to libraries like Redux by allowing for centralized state management. Context API provides the context to share state across components, while Hooks like useState and useReducer can manage that state effectively. This eliminates the need for additional state management libraries like Redux while maintaining similar functionality.
When dealing with arrays in an immutable way, rather than using push or pop methods, developers should opt for ________ or ________ methods.
- Add and Remove
- Create and Delete
- Increment and Decrement
- Shift and Unshift
When working with arrays in an immutable way, developers should opt for Shift and Unshift methods rather than using push or pop methods. Shift removes an element from the beginning of an array, and Unshift adds an element to the beginning, ensuring immutability as opposed to push and pop, which modify the end of the array.
When would you typically use a HOC in your React application?
- When applying CSS styles to components.
- When defining component state using hooks.
- When managing global state with Redux.
- When sharing component logic across multiple components.
You would typically use a Higher Order Component (HOC) in your React application when you want to share component logic across multiple components. HOCs are a pattern for reusing logic, and they are not directly related to applying CSS styles, managing global state with Redux, or defining component state using hooks.
You are building a series of components that require user authentication. Instead of adding the authentication logic to each component, which approach would be most efficient?
- Implement a higher-order component (HOC) that handles authentication and wrap each component requiring authentication with this HOC.
- Use a singleton pattern to create a single instance of an authentication service and import it into each component.
- Use Redux or a similar state management tool to store authentication information and access it from any component that requires authentication.
- Implement authentication logic directly within each component, ensuring independence and granularity.
The most efficient approach to handling authentication in a series of components is to implement a higher-order component (HOC) that encapsulates the authentication logic. This HOC can be reused to wrap each component requiring authentication, reducing code duplication and ensuring a consistent authentication process. The other options may lead to code duplication, complex management, or decreased maintainability.
For animating route transitions in a React application, you can use the ________ alongside React Router.
- "Axios"
- "Babel"
- "React Transition Group"
- "Redux"
To animate route transitions in a React application, you can use the "React Transition Group" library alongside React Router. This library provides components and hooks for adding animation effects during route changes, enhancing the user experience.
What is the primary purpose of a Higher Order Component (HOC) in React?
- To control the styling of a component.
- To create reusable logic for multiple components.
- To define the visual structure of a component.
- To manage the state of a component.
The primary purpose of a Higher Order Component (HOC) in React is to create reusable logic that can be applied to multiple components. HOCs are used to abstract and share common functionality or behavior, making it easier to maintain and reuse code across different parts of an application.
How does React's virtual DOM improve performance over direct DOM manipulation?
- It minimizes direct manipulation of the DOM.
- It eliminates the need for JavaScript.
- It reduces the size of the browser cache.
- It disables component re-rendering.
React's virtual DOM improves performance by minimizing direct manipulation of the DOM. Instead of making frequent changes to the actual DOM, React works with a virtual representation of the DOM and calculates the most efficient way to update it. This reduces browser reflows and repaints, leading to better performance. The other options are not accurate descriptions of virtual DOM's benefits.
When building a protected route in React Router, what is a common strategy to determine if a user should be redirected to a login page?
- Checking if the user's session token is valid.
- Using a regular expression to match the route path.
- Checking the browser's localStorage for a login flag.
- Sending a GET request to the server to validate the user's credentials.
A common strategy for determining if a user should be redirected to a login page when building a protected route in React Router is to check if the user's session token is valid. Session tokens often store authentication information and can be validated on the server to ensure the user is authenticated. The other options may be used for different purposes but are not typically used for this specific scenario.
For assets that change frequently, the ________ caching strategy is often more appropriate than cache-first.
- Cache-first
- Cache-only
- Network-first
- Stale-while-revalidate
For assets that change frequently, the network-first caching strategy is often more appropriate than cache-first. Network-first prioritizes fetching the latest version of a resource from the network and uses the cache as a fallback. This is suitable for frequently updated assets like API responses.