Category Archives: React JS

Flutter Vs React Native:Which Platform Is Better for Mobile App Development

If you are a mobile app developer, you must be knowing about Flutter and React native. There are so many app developing software used to develop mobile apps. Technology is growing and the demand for better and improved apps is also growing. We are using apps for everything whether it’s app health, shopping, travelling, Millions of people download apps from google play store and app store. We first need to know the difference between Flutter and React Native and how they are used to develop some of the best apps in the market. So here is a comprehensive study of Flutter Vs React Native.

Flutter

It is an open-source toolkit used to develop creative and easy to navigate applications. Flutter is released by Google in 2017. It consists of tools that are required to develop an app like widgets, testing APIs, and more. It also consists of a UI library which includes many tools and buttons that makes it easy to develop an app. Some of the applications developed using Flutter are Google Ads, Alibaba, and other Apps on Google Play Store. Flutter uses Dart, a fast programming language. Further, it is not tricky to use. 

React Native

It is an open-source mobile framework created by Facebook in 2017 that used JavaScript to develop and mobile apps. React Native android app development is one of the best frameworks to develop both Android and iOS using a single code base. It consists of many UI components and has modules written in Objective-C and Java that improve performance in video and image editing. Some of the popular apps built using react native are Facebook, Instagram, Skype, Wix, Pinterest, etc. 

Difference Between Flutter and React Native

The key difference between both frameworks is the programming language that is being used to develop an app. Flutter uses Dart to develop a mobile app which is made by Google and React Native uses JavaScript with which every app developer is familiar. 

Flutter provides fast coding using Dart as it uses one code base which means you can create two apps using the same code for iOS and Android Platform. Apps designed using Flutter are fast and smooth. 

React Native which uses JavaScript and mostly every app developer is familiar with Java so they prefer using this framework. You can create cross-platform apps using react native and it also uses one code base which means you can use the same code to develop an Android and IOS app. The community of react-native users is huge. You will get many libraries and UI frameworks and you can connect with other developers that makes it easy to learn how you can develop an app using the react native framework. 

Both the framework provides seamless performance when it comes to developing an app using any of the ones. Both Flutter and React Native have a hot reload that shows any changes made in the coding in real-time. The developing time of an app for both Flutter and React Native is different. For some Flutter could be a very useful toolkit to develop an app because it uses Google UI Toolkit which includes all the important development components in one place. On the other hand, React Native has a big community of JavaScript coders which means you get to learn from other developers and the source is big. You can connect with more developers if you face any problem during the development process.  The components in both Flutter and react-native are different. React Native uses some basic styling tools you need to use different components for both Android and IOS. On the other hand, Flutter uses a widget which means you can make easy customization. You can use your widget both for Android and IOS. 

So the question here is which toolkit is better to develop an app? Well, it depends because not all the apps can be developed using Flutter or React Native. Moreover, if you are using Flutter for the first time you could have some tough times learning it as Dart would be something new for you. The same goes for React Native if you are new with JavaScript. Both Flutter and React Native Android development are the best tool to develop apps for Android and iOS. They have their pros and cons but many companies are using one of these tool kits to design many apps which we are using every day. The cost of developing is also lower using this toolkit. It’s on you which toolkit you want to choose to develop your app.

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React Native vs Xamarin: What to choose for cross-platform app development

Nowadays, In mobile app development industries, React native, and Xamarin becomes the heated discussion regarding what platform to be used to develop apps and games.

Vital to the humming promotion of this fight and the expanding fame of these two platforms are the networks of app developers working. 

We are going to create a comprehensive  over view of React Native vs Xamarin.

Both these platforms (React Native and Xamarin) are used by mobile app developers to create fantastic apps and games for mobile devices as the platform is open source. As we know, everything has two faces, one is excellent, and the other is negative the same as these two platforms. 

It additionally comes down to the features and qualities of that innovation, which either make it the best fit for one project or the most noticeably terrible approach for another.

All things considered, how about we start with our contrasting the two with discovering the significant contrasts, investigate the essential contemplation, and decide the champ of this ceaseless platform fight. 

An Overview on Xamarin

An open-source cross-stage for mobile application development, Xamarin can be used to manufacture applications for Android, iOS, and wearable contraptions.

Offered as a bleeding-edge adventure application progression tools inside Microsoft Visual Studio IDE, Xamarin has now gotten one of the top mobile application development platforms used by various associations and endeavours. 

Besides being a free application progression platforms, it energises the development of mobile applications while using individual programming language, to be explicit C#, for both the Android and iOS structures.

Advancement condition 

Xamarin gives app developers a thorough app advancement toolkit and programming bundle. With Xamarin, developers no longer need to put their time and cash in consolidating outsider tools.

It utilises Mono execution conditions for both the platforms, for example, Android and iOS. 

Structure 

C# has developed from its earliest stages, and the Xamarin structure presently gives stable wellbeing composing, which guarantees anticipation of unforeseen code conduct. 

App working standards 

Xamarin has an MVVM design combined with two-way information restricting, which offers incredible help for community-oriented work among various divisions.

On the off chance that your advancement approach doesn’t follow an exacting presentation arranged plan, at that point, go for Xamarin as it gives high procedure adaptability. 

How precisely does Xamarin work?

In addition to the fact that C# forms the premise of this platform, yet it additionally furnishes developers with access to React to Native APIs. This feature of Xamarin helps develop fully featured back end code that can quickly be adopted by the device UI and on SDK.

An Overview on React Native

From empowering mobile developers to manufacture exceptionally proficient apps to guarantee incredible quality and expanded manageability, the interest for react native game development services makes certain to increment after some time. 

Advancement condition 

The React Native app advancement platform expects developers to follow a wide exhibit of activities and procedures to assemble a UI. 

Design 

Respond Native app advancement platform underpins measured engineering. This implies developers can order the code into various utilitarian and autonomous squares of codes. 

App working standards 

This platform follows single direction information restricting approach, which helps in boosting the general execution of the application.

In any case, through manual performance, two-way information limiting approach can be actualised, which is helpful for presenting code cognizance and in lessening complex mistakes. 

How accomplishes React Native work? 

Respond Native empowers developers to construct applications utilizing React and JavaScript. It likewise decides the structure and usefulness of the general UI. The collaboration could be offbeat, bunched, or serializable. 

More information about React Native vs Xamarin

Xamarin gives a total bundle which diminishes the need for coordinating outsider tools and libraries–so to turn into an expert in Xamarin app development, all you need is abilities and aptitude in C#, .NET and some essential working information on React Native classes. 

While then again, they are acing React Native requires exhaustive information and aptitude of JavaScript.

Since the platform doesn’t offer all-around coordinated libraries and tools, knowledge and skill of outsider sources and tools are of center significance. 

Key contrasts among React Native vs Xamarin

Most of the companies like GitHub, Trello, Slack work using Xamarin, and other few organizations like Walmart, Instagram, Facebook work using React Native.

While React, Native application offers better execution, only one out of every odd organization can bear to build up an app for every platform. 

Where Xamarin offers numerous platform support, cost-viability and efficiency, React Native permits quicker turn of events and expanded productivity.

Since Xamarin gives total equipment support, the issues of equipment similarity are diminished. Respond Native, then again, furnishes you with instant parts which lessen the requirement for composing the whole code without any preparation. 

In React Native, with combination and after interest in outsider libraries and modules, the requirement for WebView capacities is dispensed with which like this lessens the memory prerequisites.

Xamarin, then again, gives you a far-reaching toolkit with zero ventures on extra modules and outside sources. Be that as it may, this cross-platform offers confined access to open-source advancements. 

A decent quality React Native application requires more than half a month to create, which increments the advancement time and the multifaceted app nature. 

When  Xamarin?

Case #1: When you need to work using C# and .NET. 

Case #2: Thinking about the fast increment out of luck and request of IoT, in the event that you are building up an item that includes numerous equipment limits and client gadgets at that point, make creating with Xamarin your primary need. Xamarin is completely perfect with various IoT gadgets that dispose of the requirement for an outsider source for usefulness execution. 

Case #3: The progressive and necessary test cloud is most likely the best part about Xamarin. Even though Test Cloud may take up a small amount of your financial plan, this cost merits putting resources into. The test cloud reproduces the action of genuine clients as well as guarantees that your application functions admirably on different gadgets and is available to most significant clients. 

When to go for React Native?

Case #1: When it comes to game app advancement, Xamarin is certifiably not an insightful decision. Since it bolsters C# structure and AOT gathering, getting desirable outcomes and rendering is troublesome with Xamarin. A Gaming application is refreshed progressively, exceptionally intuitive, and has elite illustrations; the downside of zero similarity with overwhelming designs settles on Xamarin, a poor decision in-game app development. 

Case #2: When you need to develop a robust backend. Since numerous cell phone clients have their photographs and video stuffed in their telephone’s memory, there is scarcely any memory and capacity left for a new application. 

Pondering which structure to pick? 

Xamarin and React Native are one of the most trending platforms to develop applications and games.. Nonetheless, your choice ought to be founded on the sort of application, prerequisites and development cost.

In the event that you need a quicker development process go for the Xamarin, and on the off chance that you are building up a game, web-based business or social web-page go for React Native.

You must hear of react-native game development.

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React JS vs Angular JS

Startups, SMEs, huge enterprises like to utilize a high usefulness framework to develop vigorous web applications in a more limited time period. 

Javascript is one of the most well-known languages among developers these days. There is a lot of developers, freshers, and experienced love to assemble their application or undertaking utilizing Javascript yet at the same time there is disarray when they need to get the right framework or library for their task. 

These days, two frameworks AngularJS and ReactJS are widely utilized in web app development; that is the reason enterprises are very confounded in choosing the best one. 

What is React JS? 

React is a Javascript library developed by Facebook which permits you to assemble UI segments. It encourages the formation of intelligent User Interfaces. It likewise makes the code more obvious and dispatches. React JavaScript framework utilizes worker side delivering to give an adaptable, execution arranged arrangement. 

 

Advantages Of REACTJS 

SEO friendly: Where all the JavaScript frameworks are reactive towards SEO, ReactJS makes a grand showing in that. You can run ReactJS on the worker and the virtual DOM will be returned and delivered to your program as a customary web page. You don’t have to apply for some other stunts! 

Incredible User Interface: React Native is significantly more centered around the UI, in contrast to AngularJs. It gives your clients an exceptionally responsive interface with the assistance of JavaScript associations between the Native climate of the gadget and ReactJS Native. Hence, this expands the application’s heap time and assists with keeping it running easily with no interferences. 

JSX: It is an HTML-like syntax that gathers down to JavaScript. For JSX, markup and codes are formed in a similar record. This implies code finish gives you some assistance as you type references to your segment’s capacities and factors. When looking at Angularjs versus Reactjs, the last’s string-based templates accompany the standard disadvantages: There is no code shading in numerous editors, restricted code finishing backing, and run-time disappointments. Subsequently, ReactJS is ahead in this. 

Profoundly proficient: React.js makes its own virtual DOM where your parts are kept. This approach gives developers high adaptability and astonishing execution gains in light of the fact that ReactJS figures what change is should have been made in the virtual DOM ahead of time and updates the DOM-trees appropriately. In this design, ReactJS keeps away from exorbitant DOM operations and does refreshes in a proficient way. 

 

When to Choose to React? 

React native framework will be the ideal decision for your app in the underneath given cases: 

  • You need an app with various functions. 
  • At the point when your application development group has the ability in HTML, CSS, and JavaScript. 
  • You should utilize React when your prerequisite requests a customized app arrangement. 
  • You need to make shareable parts in your app venture. 

 

What is Angular?‬‬‬‬‬‬‬‬‬‬‬‬ 

Angular JS is an auxiliary framework for developing powerful web apps. It permits developers to utilize HTML as a template language and permits HTML’s syntax to communicate the application’s segments quickly and unmistakably. 

It is a completely included JavaScript framework that enables developing dynamic, single-page web apps. It additionally bolsters the (MVC) programming structure. 

 

Advantages of Using ANGULARJS 

Simple Decision Making: Since AngularJS is an undeniable MVC framework, it gives suppositions and usefulness out of the container. AngularJS encourages you to begin all the more rapidly without feeling threatened by dynamic. This likewise enables new developers to feel comfortable all the more rapidly and makes exchanging developers between groups all the more simple and functional. 

Developing climate: You can pick your number one climate for developing with AngularJS. Albeit the vast majority of its developers use TypeScript, you are allowed to apply Javascript or Dart. For templates, you can utilize either unadulterated HTML or pre-processors like Jade. 

Segment structure: AngularJS developed from a framework to a platform. Along these lines, you can without much of a stretch utilize its segments with different frameworks. Extra usefulness might be executed similarly as parts that achieve it totally, so as mandates that broaden the usefulness of the current segment. 

Testing in AngularJS: Initially, AngularJS was made to make it simple to compose tests for applications, particularly on the off chance that you use modules, as suggested in the official documentation. Consequently, AngularJS has a significant favorable position of testing ease which gives another motivation to pick AngularJS. 

 

When to Choose Angular? 

Angular 5 is a framework that will be the ideal decision for your app in the underneath given cases: 

  • You need to prepared to-utilize arrangements and need higher efficiency. 
  • At the point when you need a huge scope highlight rich application 
  • At the point when the development group has involvement in Java, C#, and previous versions of Angular 
  • App multifaceted nature stays Low to Medium level. 

 

Which is Better? 

Both React and AngularJS are incredible choices for single-page applications. In any case, the two of them are additionally totally various instruments. There may be explanations like React is superior to Angular or likewise the other way around. 

 

Conclusion 

Before we reach any conclusion we have to remember that there is no best framework or library. Picking a framework or library totally relies upon your venture level, necessities, and your objectives. Each framework or library has a few upsides and downsides, the same as React and Angular. From the overall elements in the event that you are an amateur or have less coding practice likewise on the off chance that you need dependability for your venture you can go with React in light of the fact that it’s the expectation to absorb information is quick and simpler additionally work in the market is higher than Angular. It may be disappointing in the event that you are picking Angular in light of the fact that after at regular intervals you will encounter significant overhauls for Angular. Something else is on the off chance that you need an out and out framework to assemble an enormous scope undertaking and love to follow the straight forward coding system at that point go with Angular. 

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React vs Angular

Let’s start with Angular 2. It is a JavaScript framework with open source, that is way much better than the first Angular. The main difference is simplification, which means that you won’t find here all those complicated modules and directives that made Angular 1 so complicated and agglomerate. The result was immediate and the performance of the technology increased greatly. Along with that, now the technology supports native app and can render on a server side.

The technology gained its popularity due to the name of its creator (Google), more than that, the framework is very easy to learn.

Yet, just like every tool, this one has its advantages and disadvantages as well. Among the assets we can list:

  • Orientation on the apps with a big amount of interactive client-side code.
  • Good solution for dynamic apps with a single page.
  • Fast development process
  • Needs less code in some classes
  • Advanced testing features
  • Model-View-Controller ballance

Lower we listed the disadvantages of the framework:

  • Relatively slow when it needs to display large amounts of data
  • Not very SEO friendly.

React JS is a library that also has open source and includes JSX compiler. The fundamental contrast of these systems is that React JS is a library to render your views, not a framework.

It became popular because of the Facebook, that backs it up. React JS is a rather SEO friendly technology. And the icing on a case is its high performance and flexibility.

The pros of the technology are:

  • It’s very compatible with SEO principles
  • UI text cases are easy to create
  • You can reuse the components easily
  • Fast with big number of elements
  • Chrome extension simplifies the debugging process

And here goes a spoon of tar in a barrel of honey:

  • Sometimes the code needs to be long
  • You have to process data changes manually
  • It is view oriented

Making decision

Before making decision investigate the licencing issues, that may occur. As we said, both technologies are open source, however there still may be some limitations connected with their usage.

Model-View-Controller pattern, that lets divide data of the project into tree category and modify each separately if it’s needed is an out-of-the-box feature of Angular 2. Which gives a huge advantage in comparison with React JS, that doesn’t have such option.

The other score one for Angular 2 is its ability to display templates writing easily. With this technology you get very clear UI for the data and can get the end result with a really intuitive approach to the UI writing less code.

React JS is more complicated with it. The technology needs special functions to control data display. You have to determine the way data is represented before it’s coded into the DOM.

Data binding is another question. Angular 2 uses two-way data binding. The data is always directed only in one way, so you always know where your data changes. And this system gets really useful when it goes about debugging.

The Performance issues are extremely important when we work with very massive apps. Angular 2 has a watcher for every binding allows to track all the progressions in Dom. One a View gets new updates, the system compares new values with primary meanings. And the problem is that the technology checks not only the meanings that changed but also all of them. This fact as you understand is a bane of Angular’s productivity.

React JS and its virtual DOM doesn’t need to check new data with the whole system. Once a user entered new data, React created a new virtual Dom and compares it with the previous one. And when the library compares and sees the difference between these two versions, the system rebuilds the virtual DOM. The procedure is performed with the server, thusly reducing the load on a browser. And while there are no active users on a site Psychology Articles, React JS performance increases.

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React JS Interview Questions

React is a JavaScript library for building user interfaces. It is based on ES6 Script Extension. ES6 is ECMA Script 2015. React provides seamless manipulation and rendering of DOM objects.

We also consider it as a Popular JavaScript framework based on Redux Architecture. React is developed and maintained by Facebook Inc. React was first created by Jordan Walke, a software engineer working for Facebook. Facebook is using React since 2011 and Instagram since 2012.

So it is a necessary skill to have in your stack. You will be considered if you are an expert in React JS.  Here are some important React Js Interview Questions and Answers useful for Javascript Interview.

What is React?

React is an open-source front-end JavaScript library that is used for building user interfaces especially for single-page applications. It is used for handling the view layer for web and mobile apps. React was created by Jordan Walke, a software engineer working for Facebook. React was first deployed on Facebook’s News Feed in 2011 and on Instagram in 2012.  Read more about – What is React JS?

What are the major features of React?

The major features of React are:

  • It uses VirtualDOM instead of RealDOM considering that RealDOM manipulations are expensive.
  • Supports server-side rendering.
  • Follows Unidirectional data flow or data binding.
  • Uses reusable/composable UI components to develop the view.

What is JSX?

JSX is a XML-like syntax extension to ECMAScript (the acronym stands for JavaScript XML). Basically it just provides syntactic sugar for the React.createElement() function, giving us expressiveness of JavaScript along with HTML like template syntax.

In the example below the text inside the <h1> tag returns as JavaScript function to the render function.

class App extends React.Component {

  render() {

    return(

      <div>

        <h1>{'Welcome to React world!'}</h1>

      </div>

    )

  }

}

What are Pure Components?

React.PureComponent is exactly the same as React. Component except that it handles the shouldComponentUpdate() method for you. When props or state changes, PureComponent will do a shallow comparison on both props and state. A component, on the other hand, won’t compare current props and state to next out of the box. Thus, the component will re-render by default whenever shouldComponentUpdate is called.

What is the difference between state and props?

Both props and state are plain JavaScript objects. While both of them hold information that influences the output of render, they are different in their functionality with respect to the component. Props get passed to the component similar to function parameters whereas the state is managed within the component similar to variables declared within a function.

What is the use of refs?

The ref is used to return a reference to the element. They should be avoided in most cases, however, they can be useful when you need direct access to the DOM element or an instance of a component.

What is Virtual DOM?

The Virtual DOM (VDOM) is an in-memory representation of Real DOM. The representation of a UI is kept in memory and synced with the “real” DOM. It’s a step that happens between the render function being called and the displaying of elements on the screen. This entire process is called reconciliation.

What is the difference between Shadow DOM and Virtual DOM?

The Shadow DOM is a browser technology designed primarily for scoping variables and CSS in web components. The Virtual DOM is a concept implemented by libraries in JavaScript on top of browser APIs.

What is React Fiber?

Fiber is the new reconciliation engine or reimplementation of the core algorithm in React v16. The goal of React Fiber is to increase its suitability for areas like animation, layout, gestures, ability to pause, abort, or reuse work and assign priority to different types of updates; and new concurrency primitives.

What is the main goal of React Fiber?

The goal of React Fiber is to increase its suitability for areas like animation, layout, and gestures. Its headline feature is incremental rendering: the ability to split rendering work into chunks and spread it out over multiple frames.

What are the controlled components?

A component that controls the input elements within the forms on subsequent user input is called Controlled Component, i.e, every state mutation will have an associated handler function.

For example, to write all the names in uppercase letters, we use handleChange as below,

handleChange(event) {

  this.setState({value: event.target.value.toUpperCase()})

}

How to create props proxy for the HOC component?

You can add/edit props passed to the component using props proxy pattern like this:

function HOC(WrappedComponent) {

  return class Test extends Component {

    render() {

      const newProps = {

        title: 'New Header',

        footer: false,

        showFeatureX: false,

        showFeatureY: true

      }

      return <WrappedComponent {...this.props} {...newProps} />

    }

  }

}

What is the context?

Context provides a way to pass data through the component tree without having to pass props down manually at every level. For example, authenticated user, locale preference, UI theme need to be accessed in the application by many components.

const {Provider, Consumer} = React.createContext(defaultValue)

What is a child prop?

Children are a prop (this.prop.children) that allow you to pass components as data to other components, just like any other prop you use. Component tree put between component’s opening and closing tag will be passed to that component as children prop.

There are a number of methods available in the React API to work with this prop. These include React.Children.map, React.Children.forEach, React.Children.count, React.Children.only, React.Children.toArray. A simple usage of children prop looks as below,

 

const MyDiv = React.createClass({

  render: function() {

    return <div>{this.props.children}</div>

  }

})

ReactDOM.render(

  <MyDiv>

    <span>{'Hello'}</span>

    <span>{'World'}</span>

  </MyDiv>,

  node

)

What is reconciliation?

When a component’s props or state change, React decides whether an actual DOM update is necessary by comparing the newly returned element with the previously rendered one. When they are not equal, React will update the DOM. This process is called reconciliation.

How to set a state with a dynamic key name?

If you are using ES6 or the Babel transpiler to transform your JSX code then you can accomplish this with computed property names.

 

handleInputChange(event) {

  this.setState({ [event.target.id]: event.target.value })

}

 

Why does React use className over class attribute?

class is a keyword in JavaScript, and JSX is an extension of JavaScript. That’s the principal reason why React uses className instead of class. Pass a string as the className prop.

render() {

  return <span className={'menu navigation-menu'}>{'Menu'}</span>

}

Why are fragments better than container divs?

  1. Fragments are a bit faster and use less memory by not creating an extra DOM node. This only has a real benefit on very large and deep trees.
  2. Some CSS mechanisms like Flexbox and CSS Grid have special parent-child relationships, and adding divs in the middle makes it hard to keep the desired layout.
  3. The DOM Inspector is less cluttered.

 

What are stateless components?

If the behavior is independent of its state then it can be a stateless component. You can use either a function or a class for creating stateless components. But unless you need to use a lifecycle hook in your components, you should go for function components. There are a lot of benefits if you decide to use function components here; they are easy to write, understand, and test, a little faster, and you can avoid this keyword altogether.

What are the advantages of React?

  1. Increases the application’s performance with Virtual DOM.
  2. JSX makes code easy to read and write.
  3. It renders both on client and server-side (SSR).
  4. Easy to integrate with frameworks (Angular, Backbone) since it is only a view library.
  5. Easy to write unit and integration tests with tools such as Jest.

 

What are the limitations of React?

  1. React is just a view library, not a full framework.
  2. There is a learning curve for beginners who are new to web development.
  3. Integrating React into a traditional MVC framework requires some additional configuration.
  4. The code complexity increases with inline templating and JSX.
  5. Too many smaller components leading to over-engineering or boilerplate.

How are error boundaries handled in React v15?

React v15 provided very basic support for error boundaries using the unstable_handleError method. It has been renamed to componentDidCatch in React v16.

What is the purpose of the render method of react-dom?

This method is used to render a React element into the DOM in the supplied container and return a reference to the component. If the React element was previously rendered into a container, it will perform an update on it and only mutate the DOM as necessary to reflect the latest changes.

ReactDOM.render(element, container[, callback])

 

If the optional callback is provided, it will be executed after the component is rendered or updated.

How to use innerHTML to React?

The dangerouslySetInnerHTML attribute is React’s replacement for using innerHTML in the browser DOM. Just like innerHTML, it is risky to use this attribute considering cross-site scripting (XSS) attacks. You just need to pass an __html object as key and HTML text as value.

In this example MyComponent uses dangerouslySetInnerHTML attribute for setting HTML markup:

function createMarkup() {

  return { __html: 'First &middot; Second' }

}


function MyComponent() {

  return <div dangerouslySetInnerHTML={createMarkup()} />

}

How events are different in React?

Handling events in React elements has some syntactic differences:

  1. React event handlers are named using camelCase, rather than lowercase.
  2. With JSX you pass a function as the event handler, rather than a string.

What will happen if you use setState() in the constructor?

When you use setState(), then apart from assigning to the object state React also re-renders the component and all its children. You would get an error like this: Can only update a mounted or mounting component. So we What will happen if you use setState() in the constructor? What will happen if you use setState() in the constructor? need to use this.state to initialize variables inside the constructor.

How do you conditionally render components?

In some cases, you want to render different components depending on some state. JSX does not render false or undefined, so you can use conditional short-circuiting to render a given part of your component only if a certain condition is true.

const MyComponent = ({ name, address }) => (

  <div>

    <h2>{name}</h2>

    {address &&

      <p>{address}</p>

    }

  </div>

)

If you need an if-else condition then use a ternary operator.

const MyComponent = ({ name, address }) => (

  <div>

    <h2>{name}</h2>

    {address

      ? <p>{address}</p>

      : <p>{'Address is not available'}</p>

    }

  </div>

)

 

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What is React JS?

React is a JavaScript library for building user interfaces. It is based on ES6 Script Extension. ES6 is ECMA Script 2015. React provides seamless manipulation and rendering of DOM objects.

We also consider it as a Popular JavaScript framework based on Redux Architecture. React is developed and maintained by Facebook Inc. React was first created by Jordan Walke, a software engineer working for Facebook. Facebook is using React since 2011 and Instagram since 2012.

It can be used to render UI for any type of device like Mobile, Desktop and tablets. React use JSX syntax to create dynamic HTML DOM objects. In JSX HTML is part of the Javascript code. JSX stands for JavaScript XML.JSX is an XML/HTML like extension to JavaScript.

According to Official reactjs.org:

React is a declarative, efficient, and flexible JavaScript library for building user interfaces. It lets you compose complex UIs from small and isolated pieces of code called “components”.

Reactjs Example:

A Simple Example of JSX:

const MyElement = <h1>Hello World!</h1>;

Features of React JS:

There is a number of features that React is Having. Let have a look at them:

#1.Declarative
Declarative views make your code more predictable and easier to debug. It renders and manipulates just the particular and right component when some change in data occurs and not the whole HTML page.

#2.Component-Based
Break the whole Applications in a simple component. Each component is responsible for some particular rendering. This makes easy to maintain and make it modular. Simple component are used to make a complex and enrich UI. Since Component is written using ES6, we can separate state from DOM.

Example of Component :

class HelloWorld extends React.Component {
  render() {
		return (
			<div>
			Hello {this.props.name}
			</div>
		);
	}
}
ReactDOM.render(
	<HelloWorld name="World" />,
	document.getElementById('hello-world')
);


#3.State Less and State Full Components:
React JS allow us to compose stateless and stateful component. Where we can decide to separate our DOM from the state. A simple stateless component can be used in the application to render the data from different states.

#4. Flexible
When it comes to flexibility, React gives freedom to the composer to create components, modules, and logic to make an application to work efficiently.

#5.Extensible
Plugins and components make it Extensible to any level. Users can create any number of Components and plugins as per convenient. It never restricts. We can use external plugins also.

#6.React Native
React has developed native libraries that are compatible with Android, iOS and UDP applications. So we can develop and deploy native applications for these Operating Systems.

#7.One-way data Flow:
In a React Js application, the components are not allowed to modify any property but can pass a call back function to do so. We can pass a set of values to the component to render the HTML with desired properties.

#8. Fast and Seamless Experience
All the above features make React Seamless and Fast. React provide a fast rendering of component because it renders only the right component where data has been changed.

Why We Should Choose React JS?

  • It is simple as an ES6 script.
  • Easy to learn and a huge community over the internet.
  • It has native libraries, so a single technology can work for mobile, and web applications.
  • It has one-way data binding.
  • It contains self- contained components.
  • Exceptional performance.
  • High flexibility, maintainability, and testability.

You have got a clear picture of React JS. What is React JS and what are the main features that let developers move towards it.

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