React Native Interview Questions for Freshers
1.What is React Native?
Answer: React Native is an open-source framework developed by Facebook for building mobile applications using JavaScript and React.
2.Explain the difference between React and React Native.
Answer: React is a JavaScript library for building user interfaces, primarily for web applications, while React Native is a framework for building mobile applications that allows developers to use React to build native mobile components.
3.What are the advantages of using React Native for mobile app development?
Answer: Some advantages of React Native include:
Reusable components
Faster development time
Cross-platform compatibility
Native performance
4.What is JSX in React Native?
Answer: JSX is a syntax extension for JavaScript used with React Native to describe what the UI should look like. It allows developers to write HTML-like code in JavaScript.
5.Explain the concept of state and props in React Native.
Answer: State is a built-in object in React Native used to store component-specific data that can change over time. Props (short for properties) are read-only data passed from parent to child components.
6.What is the purpose of the “setState” method in React Native?
Answer: The “setState” method is used to update the state of a component and re-render the component with the updated state.
7.What are the lifecycle methods in React Native?
Answer: Some lifecycle methods include:
componentDidMount()
componentDidUpdate()
componentWillUnmount()
8.Explain the concept of virtual DOM in React Native.
Answer: The virtual DOM is a lightweight copy of the actual DOM in React Native. It allows React to efficiently update the UI by only re-rendering the components that have changed, rather than re-rendering the entire DOM.
React Native Interview Questions for Intermediate Level
1.What are the differences between React Native and Flutter?
Answer: React Native uses JavaScript and React, while Flutter uses Dart. React Native provides better integration with existing web technologies, while Flutter offers better performance and UI consistency.
2.How do you handle navigation in React Native?
Answer: Navigation in React Native can be handled using libraries like React Navigation or React Native Navigation. These libraries provide components and APIs for implementing navigation between screens in a mobile application.
3.What are the AsyncStorage and SecureStorage APIs used for in React Native?
Answer: AsyncStorage and SecureStorage APIs are used for storing persistent data in React Native applications. AsyncStorage is used for storing simple data asynchronously, while SecureStorage is used for storing sensitive data securely.
4.Explain the concept of Redux in React Native and its benefits.
Answer: Redux is a predictable state container for JavaScript apps, including React Native. It helps manage the state of an application in a single immutable object, making it easier to manage and debug application state.
5.What are Higher-Order Components (HOCs) in React Native?
Answer: Higher-Order Components are functions that take a component as input and return a new component with enhanced functionality. They are commonly used for code reuse, logic abstraction, and cross-cutting concerns.
6.How do you optimize performance in React Native applications?
Answer: Performance optimization techniques in React Native include:
Using PureComponent and shouldComponentUpdate for optimizing rendering.
Implementing FlatList or SectionList for efficient rendering of large lists.
Minimizing the use of inline styles and optimizing images.
7.What are the differences between functional components and class components in React Native?
Answer: Functional components are stateless and are defined as functions, while class components have state and lifecycle methods and are defined as ES6 classes. Functional components are simpler and have better performance, while class components offer more features.
8.Explain how you would handle platform-specific code in React Native.
Answer: React Native provides a Platform module that allows developers to write platform-specific code using the “Platform.OS” property. Conditional rendering based on the platform can be done using this property to ensure that the correct code is executed on each platform.
9.What is the purpose of the “ref” attribute in React Native?
Answer: The “ref” attribute is used to get a reference to a React Native component instance. It can be used to access DOM nodes, interact with native components, or trigger imperative actions like focusing an input field.
10.Explain the concept of error boundaries in React Native.
Answer: Error boundaries are React components that catch JavaScript errors anywhere in their child component tree and log those errors or display a fallback UI instead of crashing the entire application. They help isolate errors and provide a better user experience.
11.How do you handle data fetching in React Native applications?
Answer: Data fetching in React Native can be handled using APIs like fetch, Axios, or libraries like Redux Saga or Redux Thunk. These APIs allow developers to fetch data from RESTful APIs, GraphQL servers, or other sources asynchronously.
React Native Interview Questions for Experienced Level
1.Explain the concept of Native Modules in React Native and when would you use them?
Native Modules are JavaScript modules that allow communication between JavaScript code and native code written in Java (Android) or Objective-C/Swift (iOS). They are used to access platform-specific features that are not available in React Native APIs.
2.How do you handle background tasks in React Native applications?
Background tasks in React Native can be handled using libraries like react-native-background-task or react-native-background-fetch. These libraries provide APIs for running tasks in the background, such as fetching data or performing periodic tasks.
3.Explain how you would implement push notifications in a React Native app.
Push notifications in React Native can be implemented using libraries like react-native-push-notification or Firebase Cloud Messaging (FCM). These libraries provide APIs for registering devices, sending notifications, and handling received notifications.
4.What are the best practices for organizing project structure in a large React Native application?
- Some best practices for organizing project structure include:
- Grouping related files by feature or module.
- Using meaningful names for files and folders.
- Separating components, screens, and utilities into different directories.
5.How do you handle app state persistence in React Native applications?
App state persistence in React Native can be handled using AsyncStorage, SecureStorage, or SQLite for storing data locally. For syncing data with a server, developers can use APIs like AsyncStorage for simple data or Redux Persist for managing complex state.
6.What are the benefits of using React Native for cross-platform mobile app development compared to native development?
- Some benefits of using React Native include:
- Faster development time
- Code reusability
- Hot reloading for faster iterations
- Access to a large community and ecosystem of libraries and tools
7.Explain how you would handle authentication in a React Native app.
Authentication in React Native apps can be implemented using techniques like JSON Web Tokens (JWT), OAuth, or Firebase Authentication. Developers can use AsyncStorage or SecureStorage to store tokens securely and manage user sessions.
8.How do you optimize images for better performance in React Native applications?
- Image optimization techniques in React Native include:
- Using the correct image format (JPEG for photos, PNG for logos and icons)
- Resizing images to match display dimensions
- Compressing images to reduce file size
- Lazy loading images to improve initial load time