250+ React Js MCQ With Online Practice Test

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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.

231. What is the main purpose of code splitting in a React application?

Answer: To reduce the size of the initial bundle

232. Which built-in method in React allows you to perform code splitting?

Answer: import()

233. What is the key advantage of lazy loading components in a React application?

Answer: Faster initial page load

234. In which lifecycle method can you use code splitting and lazy loading in a React component?

Answer: componentDidMount

235. How does React determine when to load a lazily loaded component?

Answer: When the component is imported

236. What is the purpose of the Suspense component in relation to lazy loading in React?

Answer: It's used to display a loading indicator

237. In React, what is the primary function of the React.lazy() function?

Answer: To wrap a component for lazy loading

238. Which error boundary component can be used to handle errors during lazy loading in React?

Answer: ErrorBoundary

239. What happens if an error occurs while loading a lazily loaded component in React?

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?

Answer: Loading large libraries or third-party code
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