1. What is a Native Module?
AdvancedAnswer: Bridge connecting JavaScript to native code
Native Modules bridge JavaScript and native code (Java/Kotlin for Android, Objective-C/Swift for iOS). Access platform APIs not exposed to JavaScript.
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React Native Interview Questions and Answers
24 questions that come up in React Native technical interviews, each with the answer and an explanation of why it is right.
Test yourself — 90 question bank2. What is React Navigation?
IntermediateAnswer: Navigation library for routing and navigation
React Navigation is the most popular navigation library for React Native. Provides stack, tab, drawer navigation and more.
3. What is React Native?
BeginnerAnswer: Framework for building mobile apps using React
React Native is a framework developed by Facebook for building native mobile applications using React and JavaScript. Write once, run on iOS and Android.
4. How do you create a Native Module?
AdvancedAnswer: Write native code and register with React Native bridge
Create native code (Java/Kotlin/ObjC/Swift), implement required methods, register with React Native bridge. Expose to JavaScript via NativeModules.
5. What is Stack Navigator?
IntermediateAnswer: Manages screen stack with push/pop transitions
Stack Navigator manages screen history as a stack. Push new screens, pop to go back. Provides native transitions and gestures.
6. What language is primarily used in React Native?
BeginnerAnswer: JavaScript/TypeScript
React Native primarily uses JavaScript or TypeScript. The code is then compiled to native components for iOS and Android.
7. How do you create a new React Native project?
BeginnerAnswer: All of the above
Multiple ways: npx react-native init (bare React Native), expo init (Expo framework), or npx create-expo-app. Each has different use cases.
8. What is Turbo Modules?
AdvancedAnswer: New native module system with better performance
Turbo Modules is the new native module system in React Native. Lazy loading, better type safety, improved performance. Part of new architecture.
9. What is the useState hook?
IntermediateAnswer: Hook for managing component state
useState is a React hook for managing component state. Returns current state and setter function: const [state, setState] = useState(initialValue).
10. What is Fabric?
AdvancedAnswer: New rendering system for React Native
Fabric is the new rendering system replacing the old bridge. Enables concurrent features, better performance, and synchronous layout. Part of new architecture.
11. What is the difference between React and React Native?
BeginnerAnswer: React is for web, React Native is for mobile
React is for building web applications using HTML/CSS. React Native is for building mobile applications using native components.
12. What is JSI (JavaScript Interface)?
AdvancedAnswer: Allows direct JavaScript-native communication
JSI allows JavaScript to directly invoke native code without bridge serialization. Foundation of Turbo Modules and Fabric. Much faster than old bridge.
13. What is the useEffect hook?
IntermediateAnswer: Hook for side effects like data fetching
useEffect handles side effects (data fetching, subscriptions, DOM updates). Runs after render. Use dependency array to control when it runs.
14. What is the View component?
BeginnerAnswer: Container component like div in web
View is the most fundamental component, similar to div in web. It is a container that supports layout, styling, touch handling, and accessibility.
15. What is the useContext hook?
IntermediateAnswer: Accesses context values without Consumer
useContext accesses context values without Consumer component. Cleaner syntax: const value = useContext(MyContext). For sharing global state.
16. What is the Text component?
BeginnerAnswer: Component for displaying text
Text component displays text content. All text must be wrapped in Text component. Supports styling, nesting, and touch handling.
17. What is Hermes?
AdvancedAnswer: JavaScript engine optimized for React Native
Hermes is JavaScript engine optimized for React Native. Reduces app size, improves startup time, lowers memory usage. Developed by Facebook.
18. How do you style components in React Native?
BeginnerAnswer: Both b and c
Use StyleSheet.create() for performance or inline style objects. No CSS files. Styles use JavaScript objects with camelCase properties.
19. What is AsyncStorage?
IntermediateAnswer: Persistent key-value storage for mobile
AsyncStorage provides persistent, asynchronous key-value storage. Like localStorage but async. Use @react-native-async-storage/async-storage package.
20. What is CodePush?
AdvancedAnswer: OTA updates without app store approval
CodePush enables over-the-air updates for JavaScript/assets without app store approval. By Microsoft App Center. Quick bug fixes and feature updates.
21. What is StyleSheet.create()?
BeginnerAnswer: Creates optimized style objects
StyleSheet.create() creates optimized style objects. Validates styles, provides better performance than inline styles, and enables style reuse.
22. What is performance optimization in React Native?
AdvancedAnswer: Use FlatList, optimize images, minimize re-renders, use native driver
Optimize performance: use FlatList for lists, optimize images (size, caching), memo/useCallback to minimize re-renders, use native driver for animations, Hermes engine.
23. What is the Animated API?
IntermediateAnswer: Built-in library for creating smooth animations
Animated API creates smooth, performant animations. Use Animated.Value, Animated.timing(), Animated.spring(). Supports native driver for better performance.
24. What is the LayoutAnimation API?
IntermediateAnswer: Animates layout changes automatically
LayoutAnimation automatically animates layout changes. Call LayoutAnimation.configureNext() before setState. Simple but less control than Animated.
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