For a component to function as an error boundary, it needs to define at least one of the two error handling lifecycle methods, ________ or ________.
- componentDidCatch
- getDerivedStateFromError
- componentWillUnmount
- componentWillMount
A React component can function as an error boundary if it defines at least the componentDidCatch method or the getDerivedStateFromError method. These methods allow the component to catch and handle errors that occur within their children. The other options are not directly related to error boundary functionality.
When integrating Websockets in a React app, where would you typically initialize the Websocket connection?
- Inside the render method of a component.
- In the componentDidMount lifecycle method.
- In the constructor of the root component.
- In the Redux store middleware.
You would typically initialize a Websocket connection in the componentDidMount lifecycle method of a React component. This ensures that the connection is established after the component has been mounted in the DOM, avoiding potential issues with trying to manipulate the DOM before it's ready. The other options are not suitable for this purpose.
How can you ensure a functional component re-renders only when certain props change?
- Use the shouldComponentUpdate lifecycle method.
- Use the memo HOC (Higher Order Component).
- Use the useEffect hook.
- Use the render method.
You can ensure that a functional component re-renders only when certain props change by using the memo HOC (Higher Order Component). This is a performance optimization that memoizes the component so that it only re-renders when its props change. The other options are either related to class components (not functional components) or are not specifically designed for this purpose.
In functional components, the ________ hook can be used to mimic the behavior of componentDidMount.
- useComponentDidMount
- useEffect
- useLifecycle
- useRenderEffect
In functional components, you can use the useEffect hook to mimic the behavior of componentDidMount. The useEffect hook allows you to perform side effects in your components, such as fetching data or setting up subscriptions, after the component has rendered. It's a crucial hook for managing the lifecycle of functional components in React.
What do we use in React to pass data from a parent component to a child component?
- JavaScript functions
- Props
- React Router
- Redux
In React, "props" (short for properties) are a way of passing data from parent to child components. They are read-only and help in component communication. Functions, React Router, and Redux serve different purposes.
React Testing Library encourages tests that utilize ________, which means your tests will focus on the end-user perspective rather than implementation details.
- shallow rendering
- component snapshots
- unit testing
- user interactions
React Testing Library encourages tests that utilize "user interactions." This means that your tests should focus on simulating and testing user interactions with your components. By doing so, you ensure that your tests mimic how a real user would interact with your application, promoting a more realistic and user-centric testing approach. The other options do not represent the primary focus of React Testing Library.
What is the key limitation of Web Workers in the context of web applications?
- Limited browser support and compatibility.
- Inability to perform background tasks.
- Lack of multi-threading capability.
- They require a dedicated GPU for optimal performance.
The key limitation of Web Workers in the context of web applications is their inability to perform background tasks. While Web Workers enable concurrent execution of code, they are not suitable for long-running or background tasks such as real-time background audio processing or background service workers. The other options are not the primary limitations of Web Workers.
What is the primary purpose of the CSSTransition component in the React Transition Group?
- Managing HTTP requests.
- Handling form validation.
- Applying CSS transitions to React components.
- Parsing JSON data in React.
The primary purpose of the CSSTransition component in the React Transition Group is to apply CSS transitions to React components. It allows you to create smooth transitions and animations when certain conditions are met, such as when a component enters or exits the DOM. It is a valuable tool for enhancing the user experience by adding visual effects to React components. The other options are unrelated to the CSSTransition component's purpose.
What is the main advantage of using lazy loading in React applications?
- Better debugging capabilities.
- Enhanced security.
- Higher quality animations.
- Improved initial load time.
Lazy loading in React applications primarily improves the initial load time of the application. It allows you to load components only when they are needed, reducing the initial bundle size and speeding up the application's first load. While other benefits like security, debugging, and animations can be indirectly impacted by lazy loading, the primary advantage is faster initial loading.
You're developing a form in React. As the form grows in complexity with multiple input fields, which hook might help you handle the form state more efficiently?
- useContext
- useEffect
- useReducer
- useState
When dealing with complex form state management in React, useReducer is more suitable than useState. useReducer provides a way to manage complex state transitions in a predictable manner, which is helpful when dealing with forms with multiple inputs and complex state logic. While useState, useEffect, and useContext have their uses, they are not as well-suited for handling complex form state.