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.
In MobX, the ________ decorator can be used to mark a method that intends to modify the state.
- @action
- @computed
- @observable
- @transaction
In MobX, the @action decorator is used to mark a method that intends to modify the state. This decorator is essential for maintaining the observability and reactivity of MobX's observable state. It signifies that the method can change the state and will trigger reactions accordingly. The other decorators (@observable, @computed, and @transaction) serve different purposes in MobX and are not used to mark methods for modifying state.
Which HTTP method is commonly used to request data from a server without making any modifications?
- GET
- POST
- PUT
- DELETE
The HTTP method commonly used to request data from a server without making any modifications is GET. It's a safe and idempotent method used for retrieving data from a specified resource without altering it. The other options, POST, PUT, and DELETE, are typically used for modifying or deleting resources on the server.
Which lifecycle method is used to catch errors in the render phase and in lifecycle methods in class components?
- componentDidCatch
- componentDidUpdate
- componentWillUnmount
- componentWillUpdate
The componentDidCatch lifecycle method is used to catch errors in the render phase and in lifecycle methods of class components. When an error occurs within a component tree, this method is invoked, allowing you to handle the error and display a fallback UI if needed. It's an essential part of error handling in React components.
A ________ allows web applications to load and function correctly even when the user is offline.
- Browser Cache
- Network Proxy
- Progressive Web App (PWA)
- Service Worker
A Progressive Web App (PWA) enables web applications to load and function correctly even when the user is offline. PWAs use service workers to achieve this functionality. While service workers play a role in this process, the correct answer directly describes the technology enabling offline functionality.
You are tasked with creating a reusable table component that should work with different data structures. Which TypeScript feature can help ensure type safety while retaining flexibility?
- Decorators
- Enums
- Generics
- Namespaces
When creating a reusable table component that should work with different data structures while maintaining type safety, Generics is the most appropriate TypeScript feature. Generics allow you to create components, functions, or classes that can work with various data types while preserving type information. Enums, Namespaces, and Decorators are not directly related to this use case.
How can you ensure smooth route transitions when navigating between different parts of a React application?
- Use React Router with CSSTransition.
- Implement route transitions with setTimeout.
- Utilize Redux for route management.
- Use React Transition Group with useState.
To ensure smooth route transitions in a React application, you can use React Router in combination with CSSTransition. This allows you to define CSS transitions/animations for route changes, creating a visually pleasing transition effect between different parts of the application. The other options are not recommended or suitable for achieving smooth route transitions.
In what scenarios might using useState be a better option than useReducer for managing local state?
- When managing simple, independent states in functional components.
- When needing to manage complex, interconnected states with multiple actions.
- useState is never a better option than useReducer for managing local state.
- When you need to manage global state across multiple components.
useState is a better option when you're dealing with simple, independent states within a functional component. useState is simpler and more concise, making it suitable for managing individual pieces of local state. useReducer, on the other hand, is more appropriate for managing complex, interconnected states where multiple actions need to be handled.
How would you ensure a React component re-renders in response to a new message received via Websockets?
- By manually calling this.forceUpdate().
- By setting shouldComponentUpdate to true.
- By using the useState hook.
- By updating the component's state using setState().
To ensure a React component re-renders in response to a new message received via Websockets, you would update the component's state using the setState() method with the new message data. This triggers a re-render of the component with the updated data. The other options are not recommended for triggering re-renders in response to data updates.