The Ultimate Guide to React Native Interview Question in 2023 (10+ Q&A)

Are you ready to embark on a journey that could potentially transform your career in app development? Are you intrigued by the world of React Native and eager to showcase your expertise in job interviews? If your answer is yes, you’ve landed on the right page.

In today’s tech-driven world, mobile app development is a rapidly growing field, and React Native has emerged as a star player. Whether you’re a seasoned developer looking to upskill or a fresh-faced coder just starting, mastering React Native is a smart move. But how do you ensure you’re well-prepared for those crucial job interviews? The answer lies in our ultimate guide: React Native Interview Questions in 2023.

The Journey Begins

Before we dive into the exciting world of React Native interview questions, let’s take a moment to understand why this framework is creating such a buzz.

React Native is an open-source framework developed by Facebook, designed to simplify the process of building mobile applications for both iOS and Android. What makes it unique is its use of JavaScript and React to create truly native experiences. With React Native, you can write code once and use it for multiple platforms, saving time and resources.

(That’s the reason why most of the job seekers who want to make a career in web development joined our React Native Course.)

But why is it important for you to prepare for React Native interviews? The answer is simple: in the competitive world of app development, demonstrating your expertise in React Native can set you apart from the crowd.

Your Roadmap to Success: React Native Interview Questions and Answers

Get ready to embark on a journey of learning and self-improvement. Below, we’ve categorized React Native interview questions into various sections to ensure you have a well-rounded understanding of this framework.

1. What is React Native? 

Answer: React Native is a framework for building native mobile applications using JavaScript and React. It allows developers to use the same codebase for iOS and Android platforms, and leverage the power of React to create declarative and reusable UI components.

2. What are the benefits of using React Native? 

Answer: Some of the benefits of using React Native are:

• Cross-platform compatibility: React Native enables developers to write one codebase that can run on both iOS and Android devices, saving time and resources.

• Hot reloading and live reloading: React Native supports hot reloading and live reloading, which means that developers can see the changes in their code reflected on the device screen without rebuilding the app or losing the app state.

• Native performance and look and feel: React Native uses native UI components and modules that interact with the native platform, resulting in high performance and native-like user experience.

• Large and active community: React Native has a large and active community of developers, contributors, and supporters, who provide helpful resources, libraries, tools, and feedback.

• Easy integration with existing code: React Native can be easily integrated with existing native code, allowing developers to use the best of both worlds.

3. What are the limitations of using React Native? 

Answer: Some of the limitations of using React Native are:

• Lack of native features: React Native does not support all the native features and functionalities that are available on iOS and Android platforms, such as advanced animations, gestures, camera, etc. Developers may need to use third-party libraries or write native modules to access these features.

• Debugging challenges: Debugging React Native apps can be challenging, especially when dealing with native errors or performance issues. Developers may need to use different tools and techniques to debug different parts of the app.

• Compatibility issues: React Native may not be compatible with some older versions of iOS and Android devices, or some third-party libraries or services. Developers may need to test their apps extensively on different devices and platforms to ensure compatibility.

• Learning curve: React Native requires developers to have a good knowledge of JavaScript, React, and native development. Developers may need to learn new concepts, tools, and best practices to use React Native effectively.

4. What are the differences between React and React Native? 

Answer: React and React Native are both frameworks for building user interfaces using JavaScript and React, but they have some key differences:

• Platform: React is a web framework that runs on browsers, while React Native is a mobile framework that runs on iOS and Android devices.

• UI components: React uses HTML elements and CSS styles to create UI components, while React Native uses native UI components that are rendered by the native platform.

• DOM manipulation: React uses a virtual DOM to manipulate the real DOM in the browser, while React Native does not use a DOM at all, but communicates with the native platform through a bridge.

• Styling: React uses CSS or CSS-in-JS libraries to style UI components, while React Native uses a subset of CSS properties and a flexbox layout system to style UI components.

5. What is Virtual DOM? 

Answer: Virtual DOM is a concept that is used by React to improve the performance and efficiency of rendering UI components. Virtual DOM is an in-memory representation of the real DOM that is created by React. Whenever there is a change in the state or props of a component, React compares the new virtual DOM with the old virtual DOM, and calculates the minimum number of changes required to update the real DOM. This process is called reconciliation. Virtual DOM helps to avoid unnecessary re-rendering of UI components, which can improve the speed and user experience of web applications.

6. How does React Native work? 

Answer: React Native works by using JavaScript and React to create UI components that are rendered by the native platform. React Native uses a JavaScript engine (such as JavaScriptCore or Hermes) to run the JavaScript code on a separate thread from the main UI thread. React Native also uses a bridge (such as MessageQueue or TurboModules) to communicate between the JavaScript thread and the native thread, and to access native modules and components. React Native leverages the power of React to create declarative and reusable UI components, and to manage the state and lifecycle of the components.

7. What are the core components in React Native? 

Answer: The core components in React Native are the basic UI elements that are provided by the framework, such as View, Text, Image, Button, ScrollView, FlatList, etc. These core components are cross-platform, which means that they can run on both iOS and Android devices with the same code. The core components can also be styled and composed to create custom UI components.

8. What are the native components in React Native?

Answer: The native components in React Native are the UI elements that are specific to a certain platform, such as DatePickerIOS, SwitchAndroid, StatusBarIOS, etc. These native components can only run on their respective platforms, and they may have different props and behaviors than the core components. The native components can be used to access some native features and functionalities that are not available in the core components.

9. What is JSX? 

Answer: JSX is a syntax extension for JavaScript that allows developers to write HTML-like code in their JavaScript files. JSX is used by React and React Native to create UI components in a declarative and expressive way. JSX is not a valid JavaScript code, but it is transformed into JavaScript code by a compiler (such as Babel) before execution.

10. How to style a React Native app? 

Answer: There are different ways to style a React Native app, but the most common way is to use the StyleSheet API that is provided by the framework. The StyleSheet API allows developers to create style objects that contain CSS-like properties and values, such as color, fontSize, margin, padding, etc. The style objects can be applied to UI components using the style prop. The StyleSheet API also supports some features such as inheritance, media queries, pseudo-selectors, etc.

11. How to create a React Native app? 

Answer:There are different ways to create a React Native app, but the most common way is to use the React Native CLI (Command Line Interface) that is provided by the framework. The React Native CLI allows developers to create a new React Native project with a simple command: 

npx react-native init <projectName>

This command will generate a basic React Native app structure with some boilerplate code and dependencies. The React Native CLI also supports some options and templates to customize the app creation process.

12. How to handle state in React Native? 

Answer: State is a term that refers to the data or information that is used by a UI component to render its content and behavior. State can be changed by user interactions, network requests, timers, etc. Handling state in React Native is similar to handling state in React, as both frameworks use the same concepts and principles. There are different ways to handle state in React Native, but the most common way is to use the useState hook that is provided by the framework. The useState hook allows developers to create and update state variables in a functional component, and re-render the component when the state changes. The useState hook takes an initial value as an argument, and returns an array with two elements: the current state value and a function to update the state value. For example:

import React, { useState } from 'react';

import { View, Text, Button } from 'react-native';

const Counter = () => {

// Create a state variable called count with an initial value of 0

const [count, setCount] = useState(0);

// Define a function to increment the count by 1

const increment = () => {

setCount(count + 1);

};

// Define a function to decrement the count by 1

const decrement = () => {

setCount(count - 1);

};

// Return a UI component that displays the count and two buttons

return (

<View>

<Text>Count: {count}</Text>

<Button title="+" onPress={increment} />

<Button title="-" onPress={decrement} />

</View>

);

};

export default App;

13. How to use Redux in React Native? 

Answer: Redux is a popular state management library that can be used in React Native apps to manage complex and shared state across multiple components. Redux works by using three main concepts: actions, reducers, and store. Actions are plain JavaScript objects that describe what happened in the app, such as user interactions, network requests, etc. Reducers are pure functions that take the previous state and an action as arguments, and return the next state based on the action type and payload. Store is an object that holds the whole state of the app, and allows components to access and update the state using dispatch and subscribe methods. To use Redux in React Native, developers need to install redux and react-redux packages, and follow these steps:

•  Define the initial state of the app as an object.

•  Define the action types as constants or strings.

•  Define the action creators as functions that return actions.

•  Define the reducer as a function that takes the state and action as arguments, and returns the next state using a switch statement or an object lookup.

•  Create the store using the createStore function from redux, and pass the reducer as an argument.

•  Wrap the root component of the app with the Provider component from react-redux, and pass the store as a prop.

•  Connect the components that need to access or update the state with the connect function from react-redux, and pass mapStateToProps and mapDispatchToProps functions as arguments.

•  Use useSelector and useDispatch hooks from react-redux to access or update the state in functional components.

For example:

// Import redux and react-redux packages

import { createStore } from 'redux';

import { Provider, connect, useSelector, useDispatch } from 'react-redux';

// Define initial state

const initialState = {

counter: 0,

};

// Define action types

const INCREMENT = 'INCREMENT';

const DECREMENT = 'DECREMENT';

// Define action creators

const increment = () => {

return {

type: INCREMENT,

};

};

const decrement = () => {

return {

type: DECREMENT,

};

};

// Define reducer

const reducer = (state = initialState, action) => {

switch (action.type) {

case INCREMENT:

return {

...state,

counter: state.counter + 1,

};

case DECREMENT:

return {

...state,

counter: state.counter - 1,

};

default:

return state;

}

};

// Create store

const store = createStore(reducer);

// Define class component that uses connect function

class CounterClass extends React.Component {

render() {

// Destructure props

const { counter, increment, decrement } = this.props;

// Return UI component

return (

<View>

<Text>Count: {counter}</Text>

<Button title="+" onPress={increment} />

<Button title="-" onPress={decrement} />

</View>

);

}

}

// Define mapStateToProps function

const mapStateToProps = (state) => {

return {

counter: state.counter,

};

};

// Define mapDispatchToProps function

const mapDispatchToProps = (dispatch) => {

return {

increment: () => dispatch(increment()),

decrement: () => dispatch(decrement()),

};

};

// Connect class component with store

const CounterClassContainer = connect(

mapStateToProps,

mapDispatchToProps

)(CounterClass);

// Define functional component that uses hooks

const CounterFunction = () => {

// Use useSelector hook to access state

const counter = useSelector((state) => state.counter);

// Use useDispatch hook to dispatch actions

const dispatch = useDispatch();

// Return UI component

return (

<View>

<Text>Count: {counter}</Text>

<Button title="+" onPress={() => dispatch(increment())} />

<Button title="-" onPress={() => dispatch(decrement())} />

</View>

);

};

// Define root component that uses Provider component

const App = () => {

return (

<Provider store={store}>

<View>

<CounterClassContainer />

<CounterFunction />

</View>

</Provider>

);

};

export default App;

14. How to test a React Native app? 

Answer: Testing is an important part of developing a React Native app, as it helps to ensure the quality, functionality, and performance of the app. Testing a React Native app can be done at different levels, such as unit testing, integration testing, end-to-end testing, etc. There are different tools and frameworks that can be used to test a React Native app, such as Jest, Enzyme, React Native Testing Library, Detox, Appium, etc. These tools and frameworks have different features and capabilities, such as mocking, snapshot testing, code coverage, automation, etc.

To test a React Native app, developers need to install the testing tools and frameworks of their choice, and follow these steps:

•  Write test cases or scenarios that describe the expected behavior and outcome of the app or its components.

•  Write test scripts or code that implement the test cases or scenarios using the testing tools and frameworks.

•  Run the test scripts or code using the testing tools and frameworks, and observe the test results and reports.

•  Fix any errors or bugs that are detected by the test scripts or code, and improve the app or its components accordingly.

•  Repeat the process until the app or its components meet the desired quality, functionality, and performance standards.

For example:

// Import testing tools and frameworks

import React from 'react';

import { View, Text } from 'react-native';

import { render } from '@testing-library/react-native';

import renderer from 'react-test-renderer';

// Define a simple UI component

const Greeting = ({ name }) => {

return (

<View>

<Text>Hello {name}!</Text>

</View>

);

};

// Write a test case using React Native Testing Library

test('renders a greeting message', () => {

// Render the component with a name prop

const { getByText } = render(<Greeting name="Alice" />);

// Expect to find the text "Hello Alice!" in the component

expect(getByText('Hello Alice!')).toBeTruthy();

});

// Write a test case using Jest snapshot testing

test('matches snapshot', () => {

// Render the component with a name prop

const tree = renderer.create(<Greeting name="Alice" />).toJSON();

// Expect the component to match the snapshot

expect(tree).toMatchSnapshot();

});

15. How to optimize a React Native app? 

Answer: Optimizing a React Native app is a process of improving the performance and efficiency of the app by reducing its size, memory usage, loading time, rendering time, etc. Optimizing a React Native app can be done at different stages, such as development stage, build stage, runtime stage, etc. There are different techniques and tools that can be used to optimize a React Native app, such as code splitting, tree shaking, minification, compression, caching, lazy loading, memoization, debouncing, throttling, etc. These techniques and tools have different effects and benefits, such as reducing bundle size, eliminating unused code, improving network requests, enhancing user experience, etc.

To optimize a React Native app, developers need to use the optimization techniques and tools of their choice, and follow these steps:

•  Analyze the current performance and efficiency of the app or its components using performance analysis tools such as Chrome DevTools, React DevTools Profiler, Flipper, Hermes, etc.

•  Implement the optimization techniques and tools using the documentation and guidelines provided by the framework or the tool.

•  Measure the improvement and impact of the optimization techniques and tools using performance analysis tools and metrics such as bundle size, memory usage, loading time, rendering time, etc.

•  Repeat the process until the app or its components reach the desired performance and efficiency standards.

Conclusion,

In this blog post, we have learned about some of the most important interview questions on React Native that can help you assess your understanding and depth on the topic. We have covered most of the common asked React Native interview questions and answers.

We hope you have enjoyed this blog post and found it useful and informative. If you want to learn more about React Native or other topics related to web development and mobile development , you can check our website or visit our Academy. If you have any feedback or questions about this blog post, feel free to leave a comment below. We would love to hear from you.