In which scenario would a network-first approach be more beneficial than a cache-first approach?

  • For static content that rarely changes.
  • In low-bandwidth network conditions.
  • When offline access is essential.
  • When real-time data updates are critical.
A network-first approach is more beneficial than a cache-first approach when real-time data updates are critical. In scenarios where data needs to be fetched from the server immediately to reflect the latest changes (e.g., social media feeds or stock prices), a cache-first approach may delay the delivery of real-time information, whereas a network-first approach ensures the freshest data is always fetched from the server.

When you want to execute a GraphQL mutation using Apollo Client in a React component, you can use the ________ hook.

  • useLazyQuery
  • useMutation
  • useQuery
  • useSubscription
In Apollo Client, when you want to execute a GraphQL mutation in a React component, you should use the useMutation hook. This hook provides a function to execute mutations and manage the state associated with it. While the other hooks (useQuery, useSubscription, and useLazyQuery) are important in GraphQL and Apollo Client, they are used for different purposes, such as querying, subscribing, and handling complex queries.

What is a potential drawback of using the Context API too extensively throughout an application?

  • Enhanced performance due to reduced re-renders.
  • Improved code maintainability.
  • Increased complexity of the component tree.
  • Simplified state management.
While the Context API is a powerful tool for state management, using it too extensively can lead to increased complexity in the component tree. This can make it challenging to understand and maintain the application's structure. It doesn't necessarily improve code maintainability, doesn't directly enhance performance, and doesn't necessarily simplify state management.

In what scenario might you choose the Context API over Redux for state management?

  • When managing simple global states or themes.
  • When you need advanced middleware support.
  • When you need server-side rendering (SSR) support.
  • When you prefer centralized state management with strict immutability rules.
The Context API can be a suitable choice over Redux when you're managing relatively simple global states or themes. Redux is more appropriate when you need advanced middleware support, centralized state management with strict immutability rules, or server-side rendering (SSR) support. The choice depends on the specific requirements of your application.

Which TypeScript feature allows you to specify types for props and state in class components?

  • Decorators
  • Generics
  • JSX syntax
  • Type assertions
Generics is the TypeScript feature that allows you to specify types for props and state in class components. By using generics, you can create reusable components that can work with different data types. While JSX syntax is used for rendering React components, type assertions are used to explicitly specify a type, and decorators are used for metadata annotations, but they are not the primary TypeScript feature for specifying types in class components.

How do you handle errors that occur within a Web Worker from the main thread in a React application?

  • Use the onerror event handler of the Web Worker object.
  • Wrap the Web Worker code in a try-catch block in the main thread.
  • Register an error event listener in the main thread.
  • There is no way to handle Web Worker errors from the main thread.
In a React application, you can handle errors that occur within a Web Worker from the main thread by registering an error event listener in the main thread. This way, you can capture and handle any errors that occur within the Web Worker and take appropriate actions in your React application. The other options do not provide standard ways to handle Web Worker errors from the main thread.

How does thunk enhance Redux?

  • By adding built-in security features.
  • By allowing asynchronous action creators.
  • By providing a styling framework.
  • By simplifying the reducer logic.
Thunk enhances Redux by enabling asynchronous action creators. Thunk is a middleware that allows you to write action creators that return functions instead of plain objects. These functions can perform async operations, making it easier to manage async flows in Redux applications.

In a chat application, you need to ensure a particular message stays in view even after new messages arrive. Which hook would assist in achieving this functionality?

  • useRef
  • useState
  • useMemo
  • useLayoutEffect
To ensure that a particular message stays in view even after new messages arrive in a chat application, you can use the useRef hook. useRef allows you to create a reference to a DOM element or any mutable value, making it useful for persisting references across renders and updates, which is what's needed to keep a message in view. The other options, while useful in other contexts, are not specifically designed for this purpose.

You have a React component that uses a third-party library for date manipulation. While testing, you notice that this library is causing issues. How can you isolate your tests from this external dependency using Jest?

  • Use Jest's jest.mock to mock the third-party library and control its behavior during testing.
  • Rewrite the third-party library's code to remove the issues it's causing.
  • Ignore the issues and proceed with testing, assuming they won't affect the test results.
  • Disable the use of third-party libraries in the test environment.
To isolate your tests from an external dependency causing issues, you should use Jest's jest.mock as described in option a. This allows you to mock the third-party library's behavior and control its responses during testing. Rewriting the library's code is impractical and not the responsibility of the test suite. Ignoring issues or disabling third-party libraries entirely are not recommended testing practices and may lead to unreliable tests.

The ability of Immutable.js to use previous data structures to efficiently create new ones without deep cloning is referred to as ________.

  • Immutable Transformation
  • Persistent Data Manipulation
  • Structural Optimization
  • Structural Sharing
The ability of Immutable.js to use previous data structures to efficiently create new ones without deep cloning is referred to as "Structural Sharing." This core concept of Immutable.js helps optimize memory usage and performance by reusing parts of the existing data structures when creating new ones. Instead of copying everything, it shares common elements, which is key to Immutable.js's efficiency and immutability.