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
191. What is React Native primarily used for?
A. Web development
B. Mobile app development
C. Desktop application development
D. Game development
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Answer: Mobile app development
192. In React Native, what is the main programming language used for writing mobile apps?
A. JavaScript
B. Java
C. Swift
D. C++
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Answer: JavaScript
193. Which platform(s) can you build mobile apps for using React Native?
A. iOS and Android
B. Windows and macOS
C. Linux and Ubuntu
D. All of the above
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Answer: iOS and Android
194. What is the primary advantage of using React Native for mobile app development?
A. It allows you to write apps for multiple platforms with a single codebase
B. It provides advanced 3D graphics support
C. It compiles apps to native machine code
D. It offers a wide range of UI components
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Answer: It allows you to write apps for multiple platforms with a single codebase
195. Which React Native component is used for creating a button?
A. <Button>
B. <TouchableOpacity>
C. <TouchableButton>
D. <Clickable>
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Answer: <TouchableOpacity>
196. What is the purpose of React Native's "bridge" between JavaScript and native code?
A. To build bridges between different programming languages
B. To facilitate communication between JavaScript and native modules
C. To create physical bridges in apps
D. To connect to external APIs
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Answer: To facilitate communication between JavaScript and native modules
197. How can you access device features like the camera or GPS in a React Native app?
A. By writing custom native modules
B. By using JavaScript libraries
C. By embedding HTML code
D. By configuring the app's settings
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Answer: By writing custom native modules
198. Which command is commonly used to start a React Native project?
A. react-create-app
B. npm init
C. npx react-native init
D. yarn create react-native-app
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Answer: npx react-native init
199. What is the name of the React Native component that serves as the fundamental building block of UI in an app?
A. <View>
B. <Layout>
C. <Block>
D. <Container>
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Answer: <View>
200. Which tool can you use to debug and inspect React Native apps while they're running on a device or emulator?
A. React DevTools
B. Xcode
C. Android Studio
D. React Native Debugger
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Answer: React Native Debugger
