For debugging purposes in Redux, the tool that allows developers to track the state changes and actions over time is called ________.
- Redux Debugger
- Redux DevTools
- Redux Inspector
- Redux Logger
Redux DevTools is the tool used for debugging Redux applications. It provides a visual interface for tracking state changes, inspecting actions, and debugging the flow of data in a Redux store. While Redux Logger is used for logging actions and state changes, it's not as comprehensive as Redux DevTools for debugging purposes. Redux Inspector and Redux Debugger are not commonly used terms.
To prevent unnecessary re-renders in functional components, you can use the ______ hook along with callback functions.
- useCallback()
- useEffect()
- useMemo()
- useRef()
To prevent unnecessary re-renders in functional components, you can use the useCallback() hook along with callback functions. useCallback() memoizes the provided function, ensuring that the function reference remains the same between renders when its dependencies haven't changed. The other hooks serve different purposes and may not prevent re-renders.
Which of the following can you use to identify and prevent unnecessary renders in a class component?
- shouldComponentUpdate method.
- useContext hook.
- useEffect hook.
- useState hook.
You can use the shouldComponentUpdate method in a class component to identify and prevent unnecessary renders. This method allows you to specify conditions under which the component should or shouldn't update. It's a key optimization technique for class components. The useEffect, useState, and useContext hooks are used in functional components and serve different purposes.
When embedding expressions in JSX, what type of expressions can be included?
- Both JavaScript and HTML expressions.
- CSS expressions only.
- HTML expressions only.
- JavaScript expressions only.
When embedding expressions in JSX, you can include JavaScript expressions only. JSX allows you to embed dynamic values and JavaScript logic within curly braces {}. HTML expressions are not directly embedded in JSX, but you can use JSX to render HTML elements. CSS expressions are not embedded directly in JSX either.
You're working on a React SPA (Single Page Application) where each route transition should have a different animation. How would you set up your routes to achieve this?
- Define custom transition components for each route
- Use CSS animations for each route transition
- Use React Router's
component - Utilize the
component
To achieve different animations for each route transition in a React SPA, you should define custom transition components for each route. This approach allows you to have full control over the animations and tailor them to specific routes. While React Router's
What does "immutable" mean in the context of data structures?
- Data structures are always empty.
- Data structures are only used in React.
- Data structures can only store integers.
- Data structures cannot be modified.
In the context of data structures, "immutable" means that once a data structure is created, its contents cannot be modified. This is a fundamental concept in functional programming and helps in ensuring predictability and preventing unintended side effects. Immutable data structures are not limited to React; they are a broader programming concept used in various contexts.
In Next.js, to provide a custom document structure, you would override the default ________ component.
- "Custom"
- "Document"
- "Layout"
- "Template"
In Next.js, to provide a custom document structure, you would override the default "Document" component. This allows you to control the HTML and head elements of the page, making it useful for customizing the overall structure and layout of your Next.js application.
In MobX, the ________ function can be used to observe changes in observables and react to those changes.
- autorun
- observe
- reaction
- transaction
In MobX, the autorun function can be used to observe changes in observables and react to those changes. When you use autorun, it will automatically track which observables are being accessed inside the provided function and trigger a re-run whenever those observables change. This is a fundamental mechanism for reacting to changes in MobX.
What is the main advantage of using something like Redux over local state?
- Centralized state management.
- Simplicity and minimal setup.
- Automatic garbage collection.
- Enhanced UI performance.
The primary advantage of using something like Redux over local state is centralized state management. Redux allows you to store application state in a single location, making it easier to manage and access across different components. While the other options may be advantages of Redux or local state in certain contexts, centralization is the core benefit.
You've been tasked with adding real-time map updates in a logistics application using React. Which combination of technologies would be most effective?
- WebSocket for real-time updates and Leaflet for maps
- REST APIs for real-time updates and Google Maps API
- GraphQL for real-time updates and Mapbox
- AJAX for real-time updates and OpenLayers
For real-time map updates in a React application, WebSocket for real-time updates and Leaflet for maps would be the most effective combination. WebSocket allows bidirectional, low-latency communication, ideal for real-time updates. Leaflet is a popular mapping library. The other options do not offer the same real-time capabilities or suitable map libraries.