Top 50 React Native Interview Questions And Answers

Day by Day many new advanced mobile apps are developed with their own unique characteristics. Apart from coding languages, Frameworks are an advanced feature that enables you to build cross-platform applications along with developing codes.

React Native is a framework developed by Facebook Company for designing mobile applications. It’s an open-source framework to develop mobile applications for Android, IOS, Windows, and macOS. This framework is written using C++, Java, Objective C, Python, and JavaScript.

This blog contains a series of React Native Interview questions and answers for both beginners and experienced candidates.

  1. What is called Framework for mobile applications?

The framework is a model that enables you to develop a single mobile application that can be installed over many devices as a native app.

2. Explain React Native.

React Native is a framework model for developing mobile applications. It is an open-source framework developed by Facebook to develop mobile applications in Android, IOS, and Windows platforms.

  1. How is React Native developed?

This framework is written in programming languages like Java, JavaScript, Python, and Objective C.

  1. Mention the latest release of React Native.

React Native 0.63 is the latest version and was released on 6th JULY 2020.

  1. Is it possible to combine Android and IOS codes to React Native?

Yes, it’s possible. We can combine both Android and IOS Codes to React Native.

  1. Mention the basic difference between React and React Native?

React is used to create Websites and React native is for developing mobile applications.

  1. How will you Install React Native?

Below are the steps to install React Native,

-Start installing Node and Watchman

-Again start installing ReactNative CLI with npm.

-Thirdly, install XCode and its command-line tools.

-Now React Native project is created by running the following command.

react-native init MyNewProject

cd MyNewProject

react-native run-ios

 

  1. What is meant by the Interaction Manager?

Interaction Manager works to improve JavaScript animations. It creates an Interaction ‘Handle’ at the start of the animation and clearing it after the application completion for animation registering.

 

  1. How do you handle multiple platforms to React Native?

React Native framework is designed to handle multiple platforms easily. App developers will write one React Native component and it will work on both Android and IOS platforms flawlessly. Facebook, the developer of React native, ensures that the Ad Manager application reuse 87% of the same code across these two platforms.

React Native also enables users to specify platform-specific versions of each component which they can combine into the rest of the space in the React Native application.

 

  1. Mention the use of Redux in React Native?

Redux is an objective state management library present inside the React Native framework and used to combine with any framework or library. Redux app helps developers to use one application state globally and it will be easy to interact with that same state from any react component.

 

  1. Explain the benefits of StyleSheet.create in React Native?

The Style sheet is a module of React Native that allows developers to create absolute style sheet references. Developers can authorize natural style object into the create () method, which freezes that objects and allocate each one with an ID. In short, Instead of creating new style objects every time, Stylesheet.create helps to create each object with a unique ID which is used in the future as a reference for the same ID’s.

So, it helps to understand the functions in codes easily adds effective meaning to low-level components.

 

  1. What are the advantages of React Native?

The main advantages of React Native are as follows,

-Comfort in working on both client as well as server-side.

-Excellently cost-effective and provides well-organized features for code reuse

-Hence, it also provides Better code readability because of the JSX feature

-Easy to integrate with other major frameworks

-Flexibility in writing UI test cases because of React.

 

  1. Explain the use of Arrow Function?

An arrow function is mainly used in reducing the mobile application’s memory consumption. It also helps in reducing the CPU time which iterate the over loops which leads to generating the components necessary for your lists.

 

  1. Explain the pure components in React Native?

Class components that extend the React are considered to be Pure Component class and treated as pure components. The React component should be considered as pure if it renders or provides the same output for the same state and properties.

 

  1. How will you navigate from one page to another in React Native?

The syntax for navigation in React Native is this.props.navigation.navigate (‘Page name to Navigate’)

 

  1. What is refs in React Native?

Refs is the Short form for Reference. Refs are used in accessing primary React elements or DOM nodes within a React component.

 

  1. State the differences between state and props.

 

STATE PROPS
States are Mutual Props are immutual
Modification of states are possible Props are constant and remain un-modifiable
One state is set the standard and updated by the object later. Props allow you to pass properties from the parent component to the child component.

 

  1. What is JSX?

JSX is Java Script XML. In simple words, JSX allows us to write simple HTML to React. After writing code, the elements should be placed or stored in DOM.

 

  1. What is App registry in React native?

App Registry is an entry point in JavaScript which is used to run all the apps to React Native. All the components of the App root must register themselves with AppRegistry.registerComponent(), next the native system loads the bundle regarding the app. Then, simply they can run the app by invoking AppRegistry.runApplication().

 

  1. Mention the type of data does Listview considers in React Native?

Developers create DataSource type of data to create Listview. React Native uses ListView as a view component that holds the list of items and displays it in a vertically scrollable tab.

 

  1. List down the features of React Native 0.61?

Some features of React Native 0.61 version are as follows,

-Quick processing and easy refreshment of application.

– For dimensional updates, the new useWindowDimensions Hook feature is provided

– React native 0.61 version is improved with CocoaPods Support

 

  1. What is API in React Native?

API is the Application Programming Interface. It acts as a software intermediary that allows any 2 applications to talk and interact with each other. You are using an API on Facebook whenever you send a text message, or check your online/offline status.

 

23.How to use Firebase in React Native?

Firebase is a mobile platform to develop very high-quality apps and increase the customers/followers count. It will give desirably more profit by its in-built features like Authentication, Cloud Messaging, Real-time database, crash reporting, and analytics. It’s a successful tool to build superlative apps in the industry. This app is highly useful for Business Professionals to continue their business unstoppable.

 

  1. How will you work on Firebase?

Firebase could be started in a few steps.

– Generate a firebase project in the Firebase console

-Retrieve apikey, authDomain, storage bucket, and DataBase URL from firebase console

-Develop a new react-native project

-Start installing firebase from npm

-Deploy it to the react-native project

  1. How will you run and Install React Native?

The below is the command to run and install React Native,

npm install –g react-native-cli

 

  1. Mention the most commonly used commands in React Native?

react-native init PROJECTNAME

react-native run-android

react-native run-ios

watchman watch-del-all

react-native link LIBRARYNAME

 

  1. Reacted Native could be used for Web? How?

Yes, React Native could be used for the web as well. Since it’s possible to run react-native APIs and its related components on the web platform.

React Native has the following features and so it becomes flexible to use it on the Web also.

 

Web interfaces with high quality: JavaScript is used to develop web applications and user interfaces. It is filled with integral quality of interactions and it is used to support multiple input modes also.

Write once, render anywhere: It functions with several React- Native DOM components. The components are well-suited with all of the React Native API.

 

  1. Describe the Gesture Responder system in React Native?

React Native provides the most powerful and popular gesture responder system, as it uses the standard library to detect user gestures such as scroll distance, single tap, double-tap, single tap confirmed, keypad typing and pinch distance. This system manages the life-span of user gestures in your app. This system also determines the official intention of users through their touch in mobile apps.

 

  1. How will you create SQLite database in React Native?

Follow the steps to create SQLite database in React Native.

-create a folder which is called ‘www’ through the Find option in the project folder

-create and open a database file

-Move and add the created file to the project

-Select a file to add

-Validate the structure of the project

 

  1. What is Fabric in React Native?

Fabric is the modern architecture of React Native which has been developed by Facebook to advance the working facility and better user experience of mobile apps than the native apps.

 

  1. Who is using React Native nowadays?

React Native is used as a foundation or base in thousands of mobile apps. Top Multinational Companies like Facebook, Uber, Instagram, Wal-Mart, Skype, Pinterest, Tencent QQ, Adidas GLITCH, JD, Baidu Mobile use the React Native framework to carry out their business more efficiently.

 

  1. Explain Dispatch in React Native?

Dispatch is one of the functions of the Redux store. You can store and deliver action. This is the primary way to trigger a state change. Utilizing React-Redux, your components can never access the store directly. The connect component delivers it for you.

  1. What are the modules required for React Native Navigation?

The below are the modules for accessing Navigation in React Native.

react-native-gesture-handler

react-native-reanimated

react-native-screens

react-native-safe-area-context

react-navigation-stack

  1. How will you create stackNavigator in react native?

const AppNavigator = createStackNavigator({

Home: {

screen: HomeScreen,

},

});

  1. How to add react navigation to react native?

Below is the command to merge react-navigation to react native,

yarn add react-navigation (or) npm install react-navigation

  1. Describe how Virtual Dom works in React Native?

Virtual DOM is a replica of the real DOM. Both are more than the same. This node tree selects and lists the elements, their attributions, contents, and properties also. Whenever any principle data alters or changes in React Native, the complete UI will be re-rendered in Virtual DOM representation. Then, the differences and variations between previous DOM representations and present virtual DOM will be counted. Lastly, the real DOM will be updated.

 

  1. Who are the competitors of React Native?

Some of the competitors of React Native are Flutter, Ionic, Xamarin, and Apache Cordova.

 

  1. What are Native Apps?

Native apps are common types of apps. These apps are developed by using the Integrated Development Environment (IDE) for any particular operating system. They are built only for particular platforms.

 

  1. How many ways are there to write React components?

There are 2 ways to write React components. They are Functional components and Class-based Components.

Functional Component returns the JSX and uses a simple function.

Class-based function implements render lifecycle method to return JSX. It uses a separate keyword ‘Class’ in function.

 

  1. Explain the Justify Content values.

Some of the Justify Content values are,

Flex-start: This acts as the default and standard value for justify-content. This explains the arrangement that flex items will start from the top and uniformly distributed and organized vertically.

Flex-end: This is just the opposite in the case of Flex start. Elements start executing from the bottom

Center: Elements will be set and placed in the middle

Space-between: Space between arranges the items along the main axis (vertical axis) and ensures it to be evenly distributed.

Space-around: Flex elements will be equally and properly distributed with equal space in and around them.

 

  1. Explain the procedure to create a Basic button in react native?

React Native framework provides the Button component as an important feature that displays the platform-specific button. Below is the example to create a platform-specific default button in React native.

Platform-specific button means the component is working on an application like IOS or Android. To work on with the Button component there are two main methods: title and onPress.

Title props are used to display text or title (in words) on the button.

onPress props is designed like a callback event which is invoked when the user presses or touches the button. This is similar to the click event functioning on a web browser.

 

  1. What do you mean by HOC in React Native?

HOC is a Higher-Order-Component. It is an advanced React Native technique to reuse the component logic many times. The function acquires a component and returns a new element as explained in the function below.

function HOC(Comp) {

return class NewComp extends Component {

render() {

return

}

}

}

  1. Mention the major issues with MVC Framework?

Mobile applications work slowly there was a huge memory wastage.

 

  1. Explain which is better. React Native or Native App.?

React Native is better than native app. Since React Native is a faster speedy framework model and allows the developers to create mobile applications that support further in both iOS and Android. The react native successfully increases the speed of mobile development stages. It is quite easier for the developers to maintain mobile applications easily which are developed from react-native. It becomes easy for the developer in bug finding and detecting and modifying it. In the Native model of framework, these features are not procedural.

 

  1. How to load data from the server?

React Native provides the Fetch API to developers which offers splendid networking needs. Also, React Native often uses the componentDidMount lifecycle method to load and deploy the records from the server.

 

  1. Explain Cross-platform Application development?

Cross-Platform Application Development is a platform for creating various software that is supported feasibly by multiple mobile operating systems.

 

  1. Explain the similarities between Native and React Native?

In both frameworks, commonly used mechanisms are, Redux Library, React Components, React lifecycle methods, and React State and Props.

 

  1. How do you upload camera images in React Native?

React Native Image Picker module helps you in picking images from your standard library or directly from the camera.

 

  1. State the number of threads that run in React Native?

4 threads run in React Native. They are React Native UI Thread (Main Thread), React Native JavaScript Thread, React Native Modules Thread, and React Native Render Thread.

 

  1. Who founded React Native?

Jordan Walke from Facebook Inc is the founder of React Native.

 

CONCLUDING HERE:

The above summarized top 50 React Native Interview questions and answers help students and even professionals to gain more knowledge and helps in assisting to face technical interviews with no threats.

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