What is the purpose of default value in context?
- To provide a fallback value when a context value is not available
- To override the context value in child components
- To provide a default value for the context provider
- To prevent child components from accessing the context value
The default value in context is used to provide a fallback value when a context value is not available. When a component consumes a context value, it looks for the context value in its ancestors. If no ancestor provides a value, the default value is used instead. The default value is typically used as a fallback or to provide a default value for the context.
What are error boundaries in React v16?
- A way to create dynamic forms
- A way to handle errors in React components
- A way to optimize rendering performance
- A way to render components outside the normal DOM
Error boundaries are a way to handle errors in React components. In React v16, error boundaries are special components that catch and handle errors that occur during rendering. This can help prevent the entire application from crashing due to an error in a single component.
How do you apply vendor prefixes to inline styles in React?
- Use the "autoprefixer" library with CSS-in-JS
- Use the "postcss" library with a custom plugin
- Use the "react-prefixer" library with inline styles
- Use the "react-style-prefixer" library with inline styles
In React, you can apply vendor prefixes to inline styles by using the "react-style-prefixer" library. This library automatically adds vendor prefixes to CSS properties based on the browser's user agent, and can be used with inline styles or CSS-in-JS solutions like styled-components or emotion.
Is it recommended to use CSS In JS technique in React?
- Yes, it is a best practice
- No, it is not recommended
- It depends on the project requirements
The decision to use CSS in JS is largely dependent on the specific project requirements and the preferences of the development team. CSS in JS can offer certain benefits, such as better modularity and encapsulation of styles, but it may not be the best choice for every project.
What is Jest?
- A package for generating test data
- A tool for simulating component rendering without deep rendering
- A package for mocking HTTP requests
- A testing framework for React
Jest is a testing framework for JavaScript applications, including React. It is developed by Facebook and is widely used in the React community. Jest includes features such as snapshot testing, mocking, and code coverage analysis. It can be used to test React components and other JavaScript code.
What is the difference between HTML and React event handling?
- HTML uses camelCase event names, while React uses kebab-case
- HTML uses inline event handlers, while React uses event listeners
- React uses synthetic events, while HTML does not
- There is no difference
The main difference between HTML and React event handling is that React uses synthetic events, while HTML does not. Synthetic events are cross-browser compatible and behave consistently across different platforms. They are also optimized for performance by pooling event objects.
How to use class field declarations syntax in React classes?
- Use the constructor method
- Use the componentWillMount lifecycle method
- Use the componentDidMount lifecycle method
- Use the class fields syntax
The class fields syntax can be used to declare class properties directly on the class without the need for a constructor method. This syntax can be used in React classes to declare state and other properties.
Can I use web components in React application?
- Yes, but it requires additional configuration
- No, React does not support web components
- Yes, web components can be used directly in React
- Yes, but it requires using a separate library
Web components can be used in a React application, but it requires additional configuration to enable support for custom elements and shadow DOM. React components can also be wrapped in web components, allowing them to be used in non-React contexts.
What is the purpose of getDerivedStateFromError?
- To handle errors that occur during rendering
- To update the component's state based on the error that occurred
- To provide additional information about the error to the user
- To log the error to the console
The getDerivedStateFromError() method is a lifecycle method in React that is called whenever an error is thrown during rendering. Its main purpose is to update the component's state with information about the error that occurred, which can then be used to render an error message or to trigger some other action in the application.
Why are inline ref callbacks or functions not recommended?
- They can cause memory leaks
- They can introduce performance issues
- They are not compatible with all browsers
- They can interfere with the component lifecycle
Inline ref callbacks or functions are not recommended because they can cause memory leaks in your application. When using an inline ref callback, the function is recreated on each render, which can result in a buildup of references that are not properly cleaned up by the garbage collector. This can lead to memory leaks over time. It is recommended to use the createRef() API or a callback ref defined outside of the component to avoid these issues.