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.
When an error boundary catches an error, it can use the ________ lifecycle method to specify what should be rendered.
- getDerivedStateFromError
- renderErrorBoundary
- componentDidCatch
- handleError
When an error boundary catches an error, it can use the getDerivedStateFromError lifecycle method to specify what should be rendered as a fallback UI. This method is used to update the component's state in response to an error. The other options (renderErrorBoundary, componentDidCatch, and handleError) are not standard lifecycle methods in React for this purpose.
To animate route transitions, you can utilize the Switch component along with the ________ prop.
- animate
- animation
- route
- transition
To animate route transitions in React applications, you can use the Switch component along with the transition prop. This combination allows you to specify the transition animation for route changes, providing a visually pleasing transition effect when navigating between different views or pages.
When comparing Context API and Redux, which of the following is a common reason developers might choose Redux?
- Lightweight footprint
- Need for a centralized store
- Seamless integration with React components
- Simplicity of use
One common reason developers might choose Redux over Context API is the need for a centralized store. Redux provides a global store where application state can be managed, making it easier to access and update state from various parts of the application. While Context API can handle state management, Redux's centralization is often preferred for larger or more complex applications where state needs to be shared across many components.
Why is immutability important in React state management?
- To make the code shorter and easier to read.
- To allow state changes without restrictions.
- To introduce complexity into code.
- To ensure predictable and bug-free state management.
Immutability is crucial in React state management to ensure predictability and bug-free behavior. When state is immutable, it cannot be changed directly, which prevents unexpected side effects and simplifies debugging. The other options are not accurate; immutability adds a level of simplicity and predictability to the code.
A component that is used to transform another component by adding additional logic or properties is called a ________.
- HOC (Higher Order Component)
- Container Component
- Stateless Component
- Functional Component
A Higher Order Component (HOC) is used to wrap or enhance other components by adding additional logic or properties. HOCs are a common pattern in React for code reuse and logic sharing. While the other options are types of components used in React, they do not specifically describe the component that adds logic or properties to another.
When using libraries like Immer, what is the term used for the function you provide that describes the state changes?
- modifyState
- mutator
- reducer
- transform
When using libraries like Immer, you typically provide a function known as a "reducer" that describes the state changes. This function takes the current state and a draft state, and you specify the changes to be made. The reducer function is a fundamental concept in libraries like Immer and Redux for managing state updates in an immutable fashion.
In class components, the method used to update the state is ________.
- this.updateState
- setState()
- changeState()
- modifyState()
In class components in React, the method used to update the state is setState(). This method is used to update the state object, and React then re-renders the component to reflect the new state. The other options are not valid methods for updating state in class components.
When integrating a third-party UI library, what should be a primary consideration to ensure compatibility with React's reactive data flow?
- Ensuring the library uses native DOM manipulation.
- Checking for component modularity.
- Verifying the library supports TypeScript.
- Confirming the library uses a different JavaScript framework.
A primary consideration when integrating a third-party UI library with React is to ensure that the library uses native DOM manipulation. React's reactive data flow relies on its Virtual DOM, so libraries that directly manipulate the DOM can cause compatibility issues and break React's rendering optimization. The other options are relevant but not the primary concern for compatibility with React's reactive data flow.
When composing multiple HOCs, it's essential to be aware of the order, as it can affect the ________ of the enhanced component.
- Functionality
- Functionality and performance
- Performance
- Render output
The order of composing Higher-Order Components (HOCs) can significantly affect the functionality of the enhanced component. HOCs can modify the behavior and appearance of a component, and the order in which they are applied can lead to different outcomes, potentially causing unexpected behavior.
You've noticed that every time a parent component's state changes, a child component re-renders even though its props remain unchanged. How might you optimize the child component to prevent unnecessary re-renders?
- Use React.memo
- Use componentDidUpdate
- Use shouldComponentUpdate
- Use useEffect
You can optimize the child component by using React.memo. This higher-order component (HOC) can wrap your child component, preventing it from re-rendering when its props remain unchanged. componentDidUpdate and useEffect are used for side effects and don't address the issue of unnecessary re-renders. While shouldComponentUpdate can be used in class components, React.memo is the recommended way in functional components.
To optimize large lists in React, you can use a technique called ______ rendering.
- Eager
- Incremental
- Lazy
- Virtual
To optimize large lists in React, you can use a technique called "Incremental" rendering. This approach renders only the visible items in a list, improving performance when dealing with extensive lists. It's a key strategy to enhance user experience in React applications, especially when handling large datasets.