In which situations might you consider using React Fragments?
- When you need to create reusable component logic.
- When you want to group multiple elements without a div.
- When you want to manage state in functional components.
- When you need to fetch data from an external API.
React Fragments are useful when you want to group multiple elements without introducing an extra div wrapper. This is beneficial for cleaner and more semantic JSX code. The other options do not directly relate to the use of React Fragments.
You notice that a component re-renders frequently, even when the data it displays hasn't changed. Which React feature can you use to prevent these unnecessary re-renders?
- PureComponent
- useMemo()
- shouldComponentUpdate()
- useEffect()
To prevent unnecessary re-renders in React when the component's data hasn't changed, you can use PureComponent. PureComponent performs a shallow comparison of props and state, and it will only re-render if there are changes. The other options, while relevant in certain cases, do not directly address the issue of unnecessary re-renders.
You are designing a Redux application that needs to make API calls. You realize that some calls depend on the result of other calls. What would be the best way to handle this scenario in Redux?
- Use Redux Middleware to coordinate API calls and dependencies between actions.
- Use Redux Observables to handle asynchronous dependencies between API calls.
- Use Redux Reducers to dispatch API call actions and manage dependencies by handling actions sequentially.
- Use Redux Thunk to dispatch actions for API calls and manage dependencies between actions within thunks.
The best way to handle API calls with dependencies in Redux is to use Redux Thunk. Thunks are functions that can dispatch multiple actions and handle asynchronous logic, making it suitable for managing dependencies between API calls. While Redux Middleware, Redux Reducers, and Redux Observables have their use cases, they are not as well-suited for managing API call dependencies.
What are props in React?
- A component's children
- A component's internal data
- A component's methods
- A component's properties
In React, props (short for "properties") are a component's input data that are passed down from a parent component. Props are read-only and cannot be changed by the child component. Props are used to customize the behavior and appearance of a component.
What are the major features of React?
- All the options
- Component reusability
- Server-side rendering
- Virtual DOM
React has several major features, including a virtual DOM, server-side rendering, and component reusability. The virtual DOM helps improve performance by minimizing the number of updates needed to the actual DOM. Server-side rendering allows React to render components on the server before sending them to the client, improving performance and SEO. Component reusability allows developers to create reusable UI components using JavaScript. One-way data binding is not a major feature of React.
Do I need to rewrite all my class components with hooks?
- Yes, it is recommended to use hooks over class components
- No, you can continue to use class components if they are working for your project
- It depends on the project requirements
React Hooks were introduced to provide an alternative way of managing state and lifecycle methods in functional components. However, class components are still fully supported in React, and you can continue to use them if they are working for your project.
How to add Google Analytics for react-router?
- Use the "google-analytics" library with the "react-router-analytics" package
- Use the "react-analytics" library with the "router-react-analytics" package
- Use the "react-ga" library with the "react-router-ga" package
- Use the "react-router-ga" library with the "google-analytics-react" package
In React, you can add Google Analytics for React Router by using the "react-ga" library with the "react-router-ga" package. This will allow you to track pageviews and events for your React Router pages in Google Analytics, and can be configured in the "index.js" or "App.js" files.
What are controlled components?
- Components that are managed by React and cannot be updated directly
- Components that are updated using refs
- Components that are updated using the setState() method
- Components that store their own state
Controlled components are components that store their state in a parent component and are updated using the setState() method. The parent component passes down the component's state as props and also passes down a function to update the state when needed. This approach allows for more control over the component's behavior and simplifies debugging.
Is it possible to use async/await in plain React?
- No, async/await is not supported in plain JavaScript
- No, async/await requires a library or framework like Redux or Apollo
- Yes, async/await can be used with plain React components
- Yes, async/await can be used with the "react-async" library
In plain React, you can use async/await to handle asynchronous operations like API calls or Promises. Async/await is a feature of ECMAScript 2017, and can be used with modern browsers or transpiled code. However, you may need to use a library or framework like Redux or Apollo to manage the async state and data flow in your application.
What is the difference between React and ReactDOM?
- React is a server-side rendering library, while ReactDOM is a client-side rendering library
- React is for creating components, while ReactDOM is for rendering components to the DOM
- React is for handling state and events, while ReactDOM is for handling rendering and updating
- There is no difference, they are the same thing
React is a library for creating components and managing the state and events of those components, while ReactDOM is a library for rendering those components to the DOM. React provides the programming interface for working with components, while ReactDOM provides the methods for rendering and updating the components in the browser.