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1)What do you mean by React?

 React is a front-end JavaScript library developed by Facebook in 2011.it mainly follows the component-based approach for building a user interface (UI) components for a single page application. It is also used for handling the view layer in both mobile and web apps. Moreover, react plays a crucial role in developing interactive mobile and web UIs.

2) What are the features of ReactJS?

The features of React JS are as follows:

1. React improves SEO performance

React boost the performance of the SEO to higher levels as a search engine faces the problem while reading JavaScript of high loaded applications.

2.  React acts as a standard for mobile app development

It provides a transition process as an ideal solution for both mobile and web applications for building rich user interfaces.

3. React makes the process of writing components easier

Using React along with JSX(java script XML) will make you write components and code clearly and efficiently.

4. React increases efficiency

As the React boost the efficiency of components by reusing them. This is the reason why it is considered as an ideal feature of React. It is considered as the most reusable system component.

5. React ensures stable code

It ensures the stability of the code of an application by making use of downward dataflow.

3) Why React is used?

 React is used for building User Interfaces (UI) due to following reasons:

• Easy to learn nature

• Simplicity

• High scalability

• Increase performance

 4) How is React different from AngularJS?

 The following table shows the major difference between AngularJS and React

5) What are the life Cycles of ReactJS?

Component lifecycle is an essential part of this platform. It contains initialization, property updates and Destruction. It is considered as a method of simply managing the state and properties of every reach component.

1.Initialization                
2.State/PropertyUpdates
3. Destruction

6) What is the purpose of render() in React.

 In React, each component must have a render() function. If more than one HTML elements needs to be rendered, then they must be grouped together inside one enclosing tag, which can be, or some other tag.

 It returns to the single react element which is the presentation of native DOM Component. This function must be kept pure i.e., it must return the same result each time it is invoked.

7) Give An Example Of Using Events?

import React from 'react';

import ReactDOM from 'react-dom';
 var StepCounter = React.createClass({
                    getInitialState: function() { return {counter: this.props.initialCounter }; },
                    handleClick: function() {      
                    this.setState({counter: this.state.counter + 1});  },
                    render: function() {
                    return

;
            }
});
 ReactDOM.render(< StepCounter initialCounter={7}/>, document.getElementById('content'));

8) Explain the Flux Concept In Reactjs?

Flux is an architectural pattern which enforces the uni-directional data flow . Facebook uses this for developing client-side web applications internally when working with React. It is not a framework or a library. This is simply a new technique which complements React and the concept of Unidirectional Data Flow.

Facebook dispatcher library is a sort of global pub/sub handler technique which broadcasts payloads to registered callbacks.

9) Explain The Difference Between The State And Props In Reactjs?

Props:

Passes in from parent component.This properties are being read by  PropsApp component and sent to ReactDOM View.

State:

Created inside component by getInitialState.this.state reads the property of component and update its value it by this.setState() method and then returns to ReactDOM view.State is private within the component.

10) What is an event in React?

Events are the triggered reactions to specific actions. Such as mouse hover, mouse click, key press, etc. Handling these events are similar to handling events in DOM elements. But there are some syntactical differences like:

1. Events are named using camel case instead of just using the lowercase.

2. Events are passed as functions instead of strings.

The event argument contains a set of properties, which are specific to an event. Each event type contains its own properties and behavior which can be accessed via its event handler only.

11) Differentiate between Real DOM and Virtual DOM.

13) What is JSX?

JSX is a shorthand for JavaScript XML. This is a type of file used by React. It utilizes the expressiveness of JavaScript along with HTML like template syntax. It makes the HTML file really easy to understand. This file makes applications robust and boosts its performance. Below is an example of JSX:

Blog

React.js is used for building web and mobile apps.

It's fast, secure, and scalable. It provides a fantastic user and developer experience. its popularity is growing as it's supported by Facebook and a vibrant community. If you are wondering which technology to choose for your project, React.js would be the best choice.

React.js is a dominating frontend JavaScript technology, and it's getting more and more popular.

Over the last few years, the number of React.js package downloads with NPM vs. the other two popular frameworks - Angular/Core and Vue - has accelerated significantly. Technology use spreads with power laws and it looks like React.js is taking over its category.

What is the React.js framework?

In short, it's a tool to build UIs – a JavaScript library for building user interfaces. it gives the developers much more freedom than Angular or Vue. 

Just like Angular is supported by Google, React.js is maintained by Facebook and a community of developers. Both are open source and free to use under the MIT license. React.js is only six years old, which makes it a relatively new technology. However, it's matured very quickly.

With JavaScript, you can build dynamic applications where the browser performs a substantial part of functions, so they can work without contacting the server. It also allows the data and interface to be updated independently in just a part of an app (without reloading it).

What does React.js do?

React is a tool to build both UI components and whole UIs – everything that concerns putting together visual elements, binding data to those elements, and specifying the logic governing it. 

React.js can be used to create user interfaces in JavaScript for different platforms. You can use ReactDOM for web applications, React Native for mobile app development (sharing the majority of code between Android and iOS), and cross-platform hybrid desktop applications with Electron.

Recently, Microsoft has also released React Native for Windows.

React.js is a frontend technology, but it can also be executed on the backend (server-rendered) and used for desktop apps. 

There are two possible approaches to using modern JavaScript frameworks – client-side rendering, where the browser downloads the code and renders the UI, or server-side rendering, where the UI is rendered on the backend.

The difference between JavaScript solutions (such as React.js) and older technologies is that JS takes over much more of the logic and document manipulation, just as if it was not server-rendered at all.

The main feature of React.js that distinguishes it from other popular JavaScript frameworks is flexibility. You can grab a library and use it to display a simple page or a view, but you can also combine React.js with other tools and use it as a framework that will lay the foundation for a complex application.

It's more than just a library as it has a vibrant ecosystem that consists of tools, libraries, and approaches. These can be used as a custom framework and toolset.

The difference between React.js and React Native

React Native has recently become an even more popular buzzword in business circles. That is because Facebook actively promotes it as the best tool for cross-platform mobile app development.

React Native uses UI elements written in React.js that can generate native IOS and Android interface components, such as buttons and animations.

With React Native you can build applications that work smoothly on iPhone and Samsung or Huawei smartphones sharing the vast majority of the code between the two platforms.

What you can build in React.js?

For a start, think about Facebook .

It's made with React.js. In 2012, Facebook Ads became challenging to manage as the social network's web application was larger and included more components.

Mark Zuckerberg stated that relying on HTML5 was one of the biggest mistakes of their organization, promising at the same time to the users (and investors) that Facebook will deliver great mobile experiences soon.

At the same time, the corporation acquired Instagram, In May 2013, React.js was officially launched. 

Since then React.js is taking over. New products are being made using it and some of the biggest and most successful digital products are incorporating React.js into their stack. This includes the world’s most renowned applications, such as:

1. Social networks (Facebook, Instagram, Pinterest, Twitter) 
2. Sharing economy platforms (Airbnb, Lyft, Uber)
3. Media sites (Yahoo!)
4. Video platforms (Netflix)
5. SaaS tools (SendGrid, Asana, InVisionApp, Zapier)

Facebook created React for their own purposes; most of their web and mobile apps are written using React.