100+ React Native Developer Interview Questions and Answers

React Native provides several navigation options, including React Navigation, React Native Navigation, and React Native Router Flux.

• React Navigation is a popular choice for implementing navigation in React Native apps.

• React Native Navigation is a native navigation library that offers better performance and smoother transitions.

• React Native Router Flux is a simple and flexible navigation library that allows for easy navigation and deep linking.

• Other options include React Nativ...read more

Redux is a predictable state container for JavaScript apps. It helps manage application state in a more organized and efficient way.

• Centralized state management

• Predictable state changes with actions and reducers

• Easier debugging and testing

• Helps in scaling and maintaining large applications

• Example: Storing user authentication state across the app

Hooks, Redux, push notification, JavaScript basics

• Hooks are a feature in React that allow you to use state and other React features without writing a class

• Redux is a state management library for JavaScript applications

• Push notifications are messages that are sent to a user's device from a server or a backend system

• JavaScript basics include understanding variables, data types, functions, and control flow

Hermes is a JavaScript engine optimized for React Native apps.

• Developed by Facebook to improve app startup time and reduce memory usage.

• Uses ahead-of-time compilation to convert JavaScript code into bytecode.

• Supports ES6 syntax and is compatible with most React Native libraries.

• Can be enabled in React Native projects by adding a single line to the configuration file.

Hooks are functions that let you use state and other React features in functional components. useRef hook is used to persist a value between renders without causing a re-render.

• Hooks are introduced in React 16.8 to allow state and lifecycle features in functional components.

• useRef hook is used to persist a mutable value that won't trigger a re-render when changed.

• It is commonly used to access DOM elements or store mutable values in functional components.

• Example: const inputRe...read more

Optimizing a React Native application involves improving performance and reducing resource usage.

• Use PureComponent and shouldComponentUpdate to prevent unnecessary re-renders

• Implement virtualized lists for long lists to improve performance

• Minimize the use of third-party libraries and optimize the ones you do use

• Use native modules for performance-critical tasks

• Optimize images and assets for smaller file sizes

Recursion is a method where a function calls itself to solve a problem, often simplifying complex tasks.

• Recursion involves a base case and a recursive case.

• Example: Calculating factorial of a number n: factorial(n) = n * factorial(n-1).

• Base case: factorial(0) = 1.

• Recursion can lead to elegant solutions for problems like tree traversals and Fibonacci series.

Props are short for properties and are used to pass data from one component to another in React Native.

• Props are read-only and cannot be modified by the child component.

• Props are passed down from parent to child component.

• Props can be any data type, including strings, numbers, objects, and functions.

• Props are accessed using the 'this.props' syntax in class components and 'props' in functional components.

• Props can have default values set using defaultProps.

IIFE stands for Immediately Invoked Function Expression, used for creating a function that is executed immediately after it is defined.

• IIFE is used to create a private scope for variables to avoid polluting the global scope.

• It is commonly used in React Native development to encapsulate code and prevent naming conflicts.

• Example: (function() { console.log('IIFE executed'); })();

To upload files in a React Native application, you can use libraries like react-native-document-picker or react-native-fetch-blob.

• Use a library like react-native-document-picker to allow users to select files from their device.

• Use a library like react-native-fetch-blob to handle the actual file upload process.

• Make sure to handle permissions and error cases properly.

• Consider using a backend server to handle the file uploads and store them.

• Test the file upload functionality tho...read more

Navigation in React Native is the process of moving between different screens or views within an app.

• Navigation allows users to move between different screens or views within an app

• React Navigation is a popular library used for navigation in React Native

• Navigation can be implemented using stack, tab, drawer, or switch navigators

• Navigation can also involve passing data between screens or handling navigation events

Function overloading and overriding are ways to create multiple functions with the same name but different parameters or implementations.

• Function overloading is when multiple functions have the same name but different parameters.

• Function overriding is when a subclass provides a different implementation of a method that is already defined in its superclass.

• In JavaScript, function overloading is not directly supported, but can be achieved using conditional statements to check t...read more

React is a JavaScript library for building user interfaces.

• React is used for creating reusable UI components.

• It uses a virtual DOM for efficient rendering.

• React allows for declarative programming.

• It was developed by Facebook and is open source.

• React Native is a framework for building mobile apps using React.

Higher order components are functions that take a component and return a new component with additional functionality.

• Higher order components allow code reuse and logic sharing between components.

• They are commonly used for adding props, state, or lifecycle methods to components.

• Example: withAuth HOC can add authentication logic to a component.

useEffect and useState are React hooks for managing side effects and state in functional components; DOM refers to the document object model.

• useState: A hook that allows you to add state to functional components. Example: const [count, setCount] = useState(0);

• useEffect: A hook that lets you perform side effects in function components. Example: useEffect(() => { document.title = `Count: ${count}`; }, [count]);

• DOM: The Document Object Model represents the structure of a documen...read more

React Native works by running JavaScript code on a separate thread and communicating with native modules through a bridge.

• React Native runs JavaScript code on a separate thread called the JavaScript thread.

• It communicates with native modules through a bridge, which allows JavaScript to interact with platform-specific APIs.

• The bridge passes messages between the JavaScript thread and the native modules, enabling seamless communication.

• React Native uses a virtual DOM to efficien...read more

Class components are ES6 classes that extend React.Component and have a render method. Functional components are simple functions that return JSX.

• Class components are created using ES6 classes and have a state property.

• Functional components are stateless and do not have a state property.

• Class components can have lifecycle methods like componentDidMount, componentDidUpdate, etc.

• Functional components are simpler and easier to read compared to class components.

• Example: Class com...read more

React is a JavaScript library for building user interfaces using components and state management.

• Components: Reusable UI elements. Example: <Button /> can be reused across the app.

• JSX: Syntax extension that allows writing HTML-like code in JavaScript. Example: const element = <h1>Hello, World!</h1>;

• State: An object that determines how that component renders & behaves. Example: this.setState({ count: this.state.count + 1 });

• Props: Short for properties, used to pass data from p...read more

JavaScript has 7 fundamental data types: Undefined, Null, Boolean, Number, BigInt, String, and Symbol.

• Undefined: A variable that has been declared but not assigned a value. Example: let x; // x is undefined

• Null: A variable that intentionally has no value. Example: let y = null; // y is explicitly set to null

• Boolean: Represents a logical entity and can have two values: true or false. Example: let isActive = true;

• Number: Represents both integer and floating-point numbers. Examp...read more

FlatList is a performant component for rendering large lists of data in React Native applications.

• Optimized for large data sets, only rendering items that are currently visible on the screen.

• Supports features like scrolling, item separators, and pull-to-refresh.

• Example usage: <FlatList data={data} renderItem={renderItem} keyExtractor={item => item.id} />

• Can handle complex data structures and custom item layouts.

A CI/CD pipeline automates the process of integrating code changes and deploying applications, enhancing efficiency and reliability.

• Continuous Integration (CI) allows developers to merge code changes frequently, reducing integration issues.

• Continuous Deployment (CD) automates the release of code to production, ensuring faster delivery of features.

• CI/CD pipelines can include automated testing to catch bugs early, improving code quality.

• Tools like Jenkins, CircleCI, and GitHub ...read more

React Native uses two types of threads: UI thread and JavaScript thread.

• UI thread is responsible for rendering the user interface and handling user interactions.

• JavaScript thread is responsible for executing JavaScript code and handling business logic.

• UI thread and JavaScript thread communicate with each other through a bridge.

• UI thread is a native thread managed by the operating system.

• JavaScript thread is a separate thread managed by the JavaScript engine.

• UI thread should n...read more

Custom hooks in React Native allow you to reuse stateful logic across multiple components.

• Create a function that starts with the word 'use' (e.g., 'useCustomHook')

• Inside the custom hook, define and initialize any state variables or functions you need

• Return the state variables and functions as an array or object

• Use the custom hook in any component by calling it and destructuring the returned values

Code quality is maintained through code reviews, automated testing, coding standards, and continuous integration.

• Regular code reviews by peers to catch errors and ensure best practices are followed

• Implementing automated testing to catch bugs early in the development process

• Enforcing coding standards and guidelines to maintain consistency and readability

• Utilizing continuous integration tools to automate the build and testing process

Context is a feature in React that allows data to be passed down the component tree without manually passing props. Hooks are functions that allow you to use state and other React features in functional components.

• Context is used to share data between components without passing props explicitly

• Hooks are functions that allow you to use state and other React features in functional components

• Context provides a way to pass data through the component tree without having to pass pr...read more

let is block scoped, var is function scoped, const is a constant variable.

• let is block scoped, meaning it is only accessible within the block it is declared in.

• var is function scoped, meaning it is accessible throughout the function it is declared in.

• const is a constant variable, its value cannot be reassigned once it is initialized.

React is a JavaScript library for building user interfaces, while React Native is a framework for building mobile applications using React.

• React is a JavaScript library developed by Facebook for building user interfaces.

• React allows developers to create reusable UI components.

• React Native is a framework that allows developers to build mobile applications using React.

• React Native enables developers to write code once and deploy it on multiple platforms.

• React Native uses native...read more