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 situations where the next state depends on the previous state, it's recommended to use a ________ function with setState or useState.
- asynchronous
- callback
- immutable
- sync
In situations where the next state depends on the previous state, it's recommended to use a callback function with setState or useState. This is because JavaScript's state updates can be asynchronous, and using a callback ensures that you're working with the latest state when updating it.
In the Render Props pattern, the component that shares its state or functionality is typically invoked as a ________.
- Child Component
- Wrapper Component
- Parent Component
- Functional Component
In the Render Props pattern, the component that shares its state or functionality is typically invoked as a Wrapper Component. The Wrapper Component defines a render prop, allowing the child component to access and utilize the shared state or functionality. This pattern is used to share behavior or data between components in a flexible way. The other options do not accurately describe the role of the component that shares its state in the Render Props pattern.
What does the Link component in React Router replace in traditional HTML?
- tag
-
tag
- tag
The Link component in React Router replaces the traditional HTML (anchor) tag. It is used for navigating between different routes in a React application without causing a full page refresh. The Link component provides a seamless client-side routing experience.
Which popular library in React allows you to write actual CSS code inside your JavaScript?
- Axios
- Reactstrap
- Redux-Saga
- Styled-components
Styled-components is a popular library in React that enables developers to write actual CSS code inside their JavaScript files. It offers a CSS-in-JS solution, making it easier to style React components. Reactstrap is a library for Bootstrap components, Redux-Saga is for managing side effects, and Axios is for making HTTP requests, none of which are primarily focused on writing CSS inside JavaScript.
What is the primary benefit of using Web Workers in a React application?
- Better SEO optimization.
- Enhanced code maintainability.
- Improved user interface responsiveness.
- Reduced development time.
The primary benefit of using Web Workers in a React application is improved user interface responsiveness. Web Workers allow you to run JavaScript code in the background, preventing UI-blocking tasks from slowing down the user interface. This results in a more responsive and smoother user experience. While other benefits may be relevant, such as code maintainability or SEO optimization, they are not the primary focus of using Web Workers in React.