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
231. What is the main purpose of code splitting in a React application?
A. To reduce the size of the initial bundle
B. To increase development speed
C. To improve SEO
D. To manage state
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Answer: To reduce the size of the initial bundle
232. Which built-in method in React allows you to perform code splitting?
A. import()
B. require()
C. split()
D. codeSplit()
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Answer: import()
233. What is the key advantage of lazy loading components in a React application?
A. Faster initial page load
B. Better SEO
C. Enhanced security
D. Improved code readability
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Answer: Faster initial page load
234. In which lifecycle method can you use code splitting and lazy loading in a React component?
A. componentDidMount
B. componentWillUnmount
C. constructor
D. render
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Answer: componentDidMount
235. How does React determine when to load a lazily loaded component?
A. When it's explicitly requested by the user
B. When it's mentioned in package.json
C. When it's defined in the index.html
D. When the component is imported
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Answer: When the component is imported
236. What is the purpose of the Suspense component in relation to lazy loading in React?
A. It's used to display a loading indicator
B. It defines component state
C. It optimizes CSS styles
D. It fetches data from an API
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Answer: It's used to display a loading indicator
237. In React, what is the primary function of the React.lazy() function?
A. To wrap a component for lazy loading
B. To configure routing
C. To set state in a component
D. To apply styling to a component
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Answer: To wrap a component for lazy loading
238. Which error boundary component can be used to handle errors during lazy loading in React?
A. ErrorBoundary
B. SuspenseBoundary
C. LazyError
D. LoadingBoundary
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Answer: ErrorBoundary
239. What happens if an error occurs while loading a lazily loaded component in React?
A. The error is caught and can be handled
B. The application crashes
C. The component is skipped
D. The user is redirected to the homepage
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Answer: The error is caught and can be handled
240. What is a common use case for code splitting and lazy loading in a React application?
A. Loading large libraries or third-party code
B. Managing global application state
C. Animating UI elements
D. Configuring Webpack settings
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Answer: Loading large libraries or third-party code
