Top 72 React Native Interview Questions And Answers

Question 1

What is React Native?

Accepted Answer

- `React Native` is a mobile app development framework that enables the development of multi-platform **Android** and **iOS** apps using native UI elements. 
- It is based on the *JavaScriptCore* runtime and *Babel* transformers. With this setup react native supports new `JavaScript` (ES6+) features, e.g. arrow functions, async/await etc.
- This famous framework for **mobile app development** started in the summer of 2013 as Facebook’s internal hackathon project. 
- Its first public preview was released in January of 2015 at `Reactjs` Conference and in March of 2015, Facebook made React Native open and available on GitHub.

Question 2

What are the advantages of hybrid apps over native apps?

Accepted Answer

- Works across multiple platforms.
- Unified development.
- Faster build and lower cost of development.
- Easier to make changes and update.

Question 3

What are hybrid apps?

Accepted Answer

- Hybrid mobile apps are applications that are installed on a device, just like any other app.
- Hybrid apps are deployed in a native container that uses a mobile `WebView` object. When the app is used, this object displays web content thanks to the use of web technologies (`CSS`, `JavaScript`, `HTML`).

Question 4

Why do we use curly brace while importing some library?

Accepted Answer

Curly braces are used to import **small** pieces of library. 
In above example we just want to make use of `Text` and `StyleSheet` component from react-native, so they are put in curly braces.

Question 5

List some benefits of using React Native for building mobile apps?

Accepted Answer

Some benefits of React Native are:

- Known for Optimal Performance
- Can Reuse the Codes and Pre-Developed Components
- Large Community of Developers
- Advantage of Live and Hot Reloading
- Cost Effective Solution
- Offers Simple User Interface
- Support for Third-Party Plugins
- Modular Architecture
- Providing Handy Solutions and Libraries

Question 6

What are native apps?

Accepted Answer

- Native mobile apps are the most common type of app. 
- They are built for specific platforms and are written in languages that the platform accepts. For example, `Swift` and *Objective-C* for native **iOS** apps and `Java` or `Kotlin` for native **Android** apps. 
- Native apps are also built using the specific *Integrated Development Environment* (IDE) for the selected operating systems

Question 7

What is JSX?

Accepted Answer

- **JSX** is an *XML/HTML*-like syntax used by `React` that extends *ECMAScript* so that XML/HTML-like text can co-exist with `JavaScript/React` code. - The syntax is intended to be used by **preprocessors** (i.e., transpilers like Babel) to transform HTML-like text found in `JavaScript` files into standard JavaScript objects that a JavaScript engine will parse. ```js const nav = (

); ```

Question 8

How do you dismiss the keyboard in react native?

Accepted Answer

Using `Keyboard.dismiss()`

```jsx
import { Keyboard } from 'react-native'

// Hiding the keyboard
Keyboard.dismiss()
```

Question 9

What are props in React Native?

Accepted Answer

- The properties of React Native components are simply pronounced as **props**. - In React Native, most of the components can be customized at the time of their creation with different parameters. These parameters are known as **props**. - They are **immutable**, and they cannot be changed. ```jsx import React, { Component } from 'react'; import { Platform, StyleSheet, Image, Text, View } from 'react-native'; export default class App extends Component<{}> { render() { let imagePath = { uri: 'https://facebook.github.io/react-native/img/header_logo.png'}; return ( Welcome to React Native! ); } } const styles = StyleSheet.create({ container: { flex: 1, justifyContent: 'center', alignItems: 'center', backgroundColor: '#a7a6a9', }, welcome: { fontSize: 30, textAlign: 'center', margin: 20, } }); ``` Output ![React Native Props](https://static.javatpoint.com/tutorial/react-native/images/react-native-props-output.png)

Question 10

What are the advantages of native apps over hybrid apps?

Accepted Answer

-   They work efficiently as they are built for that specific platforms
-   Native apps are responsive on all the platform-specific devices
-   They are very fast and the best in the app performance
-   Native apps better integrate with mobile hardware
-   They have interactive and intuitive User Interface (UI) and User Experience (UX) as per the user expectations based on specific platforms
-   Some of the Native mobile apps work even without the Internet connection
-   Native apps are secured and reliable
-   They can easily access or utilize the other device-specific capabilities like GPS, Camera, Contacts, etc.

Top 72 React Native Interview Questions

What is React Native?

List some benefits of using React Native for building mobile apps?

Why do we use curly brace while importing some library?

What are the advantages of hybrid apps over native apps?

What are hybrid apps?

What are native apps?

What are the types of data that control a component?

What determines the size of a component and what are the ways?

What are some ways of styling a react native component?

What does the Gesture Responder System do?

What are Refs used for in React Native?

How do you dismiss the keyboard in react native?

What are the advantages of native apps over hybrid apps?

Will this piece of code work?

What are components?

When would you use ScrollView over FlatList or vice-versa?

Tell us some options of storing persisting data in a react native app?

What is JSX?

How is React Native different from ReactJs?

What are props in React Native?

What is the use of FlatList?

How are Hot Reloading and Live Reloading in React Native different?

Explain the use of Flexbox in React Native?

How are props and state different?

What does TouchableHighlight do and when do you use it?

What is State in react native?

What are Touchable Interactions in React Native?

What is "Fast Refresh"?

What is flex dimension and how is it different from fixed dimension?

How do you style a component in react native?

How do you perform logging in React native?

What are some features of Fast Refresh?

What is AppRegistry? Why is it required early in "require" sequence?

What does StyleSheet.create do and why is it useful?

How do you re-render a FlatList?

How is flexbox different in React Native and browser?

What happens if you edit modules with exports that aren't React components in Fast Refresh?

What is the use of ScrollView component?

In Fast Refresh, what will happen if you edit files imported by modules outside of the React Tree?

What are some best practices to consider for an action?

What is Lifting State Up?

What happens if you edit a module that only exports React components in Fast Refresh?

What is "autolinking" in react-native?

What is View and how important is it?

What are some limitations of using react-native-cli for instantiating a project?

What is AsyncStorage and how do you use it?

What are the features of Container/Smart components?

Does React Native compile JavaScript into Java for Android?

What are some advantages of Component Driven Development?

How would you implement animations on events?

State the lifecycle of Gesture Responder System?

What is Component Driven Development (CDD)?

What are Container/Smart components?

What are Presentational/Dumb Components?

How many threads run in a React Native app?

What does React Native Packager do in the React Native?

Differentiate ScrollView and FlatList?

What are features of presentational/dumb components?

Are libraries such as TypeScript that compile to JavaScript compatible with React Naive?

What is Higher Order Component or HOC?

What JavaScript engine does React native use?

What are the disadvantages of StyleSheet.create?

How is InteractionManager important?

How does the Fabric architecture work?

What are some benefits of Container-Presentational pattern?

What is InteractionManager and how is it used?

What is wrong with this code for querying a native API?

What is Fabric in React Native?

Does React Native have a Virtual DOM?

How do you check if the react native app is in debug or release build?

What will be the output of following snippet?

How to fetch data from local JSON file on React Native?