React.js, often simply called React, is a highly popular JavaScript library for building user interfaces. Developed and maintained by Facebook, React is renowned for its component-based architecture and the ability to efficiently update and render components when data changes. It is a foundational tool for developing modern web and mobile applications, allowing developers to create dynamic and interactive user interfaces with ease. React's vast ecosystem, including tools like React Native for mobile app development, makes it a top choice for frontend development and a key player in the world of web technologies.
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Practice Test
171. Which tool is commonly used for inspecting and debugging React components in the browser?
A. React DevTools
B. Redux DevTools
C. Webpack DevServer
D. Babel
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Answer: React DevTools
172. In React DevTools, what is the purpose of the "Components" tab?
A. To view a list of installed npm packages
B. To browse and inspect React component tree
C. To edit the app's source code
D. To check the network requests
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Answer: To browse and inspect React component tree
173. What does the "Props" panel in React DevTools display?
A. The list of installed npm packages
B. The state of the Redux store
C. The properties and values of a component
D. The app's source code
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Answer: The properties and values of a component
174. In React DevTools, what does the "State" panel show for a selected component?
A. The list of installed npm packages
B. The state of the Redux store
C. The component's local state
D. The app's source code
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Answer: The component's local state
175. How can you open React DevTools in a web application?
A. By installing it as an npm package
B. By using the browser's built-in developer tools
C. By importing it into the app's code
D. By using a third-party extension
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Answer: By using the browser's built-in developer tools
176. What does the "Profiler" tab in React DevTools help you analyze?
A. Component rendering performance
B. Redux actions and reducers
C. Network requests and responses
D. Code coverage and testing
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Answer: Component rendering performance
177. What is the purpose of the "Hooks" tab in React DevTools?
A. To display a list of available React hooks
B. To browse and inspect the component tree using hooks
C. To edit the app's source code using hooks
D. To analyze performance of custom hooks
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Answer: To browse and inspect the component tree using hooks
178. In React DevTools, what does the "DOM" tab show?
A. The Document Object Model (HTML structure)
B. The Redux state
C. The application's dependencies
D. The app's source code
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Answer: The Document Object Model (HTML structure)
179. Which of the following statements about React DevTools is true?
A. It's a separate application from the browser's developer tools
B. It only works with Redux applications
C. It requires a paid subscription for use
D. It's limited to inspecting React components
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Answer: It's a separate application from the browser's developer tools
180. What does the "Settings" tab in React DevTools allow you to configure?
A. Display options for the developer console
B. Custom keyboard shortcuts
C. Theme and color scheme options
D. Application performance settings
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Answer: Custom keyboard shortcuts
