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React Native is an open-source Javascript framework introduced by Facebook. It is used in iOS and Android platforms. The application is based on React which is a javascript library developed by Facebook and XML-Esque markup (JSX) for creating the user interface. This is a mobile app that is based on cross-platform used for developing a mobile application for iOS, Android, and Windows.
In this article, you can go through the set of react-native interview questions most frequently asked in the interview panel. This will help you crack the interview as the topmost industry experts curate these at HKR training.
Let us have a quick review of the react-native interview questions.
Ans: These are the apps which run on mobile devices but are not loaded over the browsers as they are not web applications. The react native apps are also not the hybrid apps that are built over Ionic, Phonegap which run on WebView component. It is a real native app which is built only in JavaScript with the native components to run on mobile devices.
Ans: The differences between React and React Native are:
Ans: The core components include.
Ans: The benefits of using React Native are.
Ans: The React Native applications run the following threads.
Ans: An API is a software interface in which any two applications can be communicated with each other without knowing how they are implemented. React Native uses the Fetch networking API which simply calls the URL through Fetch and then it makes requests to server as needed. The React Native implements mainly three lifecycle methods which are constructor, componentDidMount and Render.
Ans: By calling “setState” the react will merge the object that is passed into setState into the current state of the component. It then kicks off the reconciliation process. The goal of reconciliation is to update the UI based on this new state in the most efficient possible way.
To perform this, React will construct a new tree which contains the React elements. The tree is an object representation of your UI. This tree is developed for finding out how UI should change in response to the new state, React will diff this new tree against the previous element tree.
Ans: The JSX stands for JavaScript XML. It is a syntax notation for JavaScript XML. JSX provides expressiveness of JavaScript with HTML like template syntax.
Example: The below text inside the
render(){
return(
);
}
Ans: Hooks let your use state and other React features without writing a class. It is a new addition released in React 16.8. Hooks extracts stateful logic from a component that can be tested independently and will be reused. It resues stateful logic without changing the component hierarchy which makes it easy to share Hooks among many components or with the community.
Ans:
Ans:
1.By using the below statement
const customData = require('./customData.json');
and then access customData like a normal JS object.
2.For ES6/ES2015 you can import directly like:
// app.js
import * as data from './example.json';
const word = data.name;
console.log(word); //
output 'testing'
Ans:
Example: If four links are used deep into your navigation and saved a change, live reloading would restart the app and load the app back to the initial route.
Example: If four links are used deep into your navigation and saved a change to some styling, the state would not change but the new styles would appear on the page without having to navigate back to the page you are on because you would still be on the same page.
Ans: The React Native Packager performs the following functionalities:
Ans: React Native 0.61 is the latest version which can optimize the features of the version 0.60. The latest release of React Native comes with the following improvements. It has incorporated four advanced level features as below.
Ans:
Example: The below code creates a View that wraps two coloured boxes and a text component in a row with padding.
class ViewColoredBoxesWithText extends Component {
render() {
return (
style={{
flexDirection: 'row',
height: 100,
padding: 20,
}}>
Hello World!
);
}
}
Ans:
Example:
const styles = StyleSheet.create({
container: {
borderRadius: 4,
borderWidth: 0.5,
borderColor: '#d6d7da',
},
title: {
fontSize: 19,
fontWeight: 'bold',
},
activeTitle: {
color: 'red',
},
});
Ans: The best UI Components for React Native are.
Ans: Create a simple "Hello World" app by using modifying “App.js” file of FirstApp. Save the utility and reload by way of in reality pressing twice "R" or Ctrl+M (Reload).
Example:
import React, {Component} from 'react';
import {Platform, StyleSheet, Text, View} from 'react-native';
type Props = {};
export default class App extends Component {
render() {
return (
Hello World
);
}
}
Ans:
Ans: The animation is a method which manipulates the images to appear it as moving objects. React Native animations allows to add extra effects that can provide good user experience in the app. It can be used with React Native API, Animated.parallel, Animated.decay, and Animated.stagger.
There are two types of animation in react native, which are given below.
Ans: The following steps are used in creating the SQLite database in react native.
Ans: Redux is a state management tool. It is a state container for JavaScript applications. It helps to write applications which can consistently run on a different environment and are easy to test.
React Native use Redux to allow the developers to use one application state as a global state and interact easily with the state from any React component. It can combine with any framework or library.
Ans: Upgrading React Native with the latest version gives access to more APIs, views, developer tools and other features. The following steps are implemented for upgrading.
Ans: This is an example to call the web service in React Native.
fetch('http://**someurl**', {
method: 'POST',
headers: {
'Accept': 'application/json',
'Content-Type': 'application/json',
},
body: JSON.stringify({
username : "admin123",
password: "password123",
})
})
Ans: The following steps should be followed to install React Native.
react-native init MyNewProject
cd MyNewProject
react-native run-ios
Ans: Handling multiple platforms is easy for React Native. The majority of React Native APIs are based on cross-platform, this makes the app developers write one React Native component, that can work on both iOS and Android seamlessly. It also allows users to specify platform-specific versions of each component that can integrate into the rest of the React Native application.
Ans: It is a native module of React Native which works by deferring the execution of a function until an “interaction” has finished. The interactive manager is a crucial module because React Native has only one thread for making UI updates which can be overloaded and result in drop frames. Developers use the interaction manager to ensure that the function is only executed after the animations occurred so that any frame drops may not result.
Ans: The main differences between React Native and Ionic are.
Ionic:
It is a typical hybrid development framework. It mainly handles all the look and feel of your app which focuses on front-end user experience or UI interaction. It is can integrate with other libraries or frameworks such as Angular, Cordova, React, etc. It is easy to learn and its purpose is to write once and runs everywhere.
React Native:
It is an open-source JavaScript framework developed by Facebook to build a cross-platform mobile app. React Native is used for developing a mobile application for iOS, Android, and Windows. React Native is the equivalent to React but differs in using the native components instead of web components as building blocks. Its purpose is to learn once and write anywhere and targets mobile platforms rather than the browser.
Ans:
The Axios helps the user to send GET, POST, PUT, and DELETE requests to the REST API and render a response to the application. Axios will make the users interact with the REST API. It is a promised HTTP client used by the react-native.
Axios has a number of features.
Ans: The main differences between React Native and Xamarin are.
React Native:
It is an open-source JavaScript framework developed by Facebook to build a cross-platform mobile app. React Native is used for developing a mobile application for iOS, Android, and Windows. React Native is the equivalent to React but differs in using the native components instead of web components as building blocks. Its purpose is to learn once and write anywhere and targets mobile platforms rather than the browser.
Xamarin:
It is an open-source, cross-platform development framework used in building the android, iOS, Windows, and Mac apps using C#. It was first launched in May 2011 by Xamarin Company. In 2016, Microsoft had signed an agreement to acquire Xamarin.
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