What is React?

Introduction to React

React is a JavaScript framework used to build the Graphical User Interface of web-based applications. Mobile Applications or single-page web applications are built using this JavaScript library for the web-based framework. The programming code for React comprises components, classified as functional components and class-based components. It is implemented using the Document Object Model (DOM), Virtual DOM, JSX (JavaScript XML) and Lifecycle methods such as ‘render’, ‘shouldComponentUpdate’, ‘componentDidMount’ and ‘componentWillUnmount’.

Features of React

Given below are some essential and most demanding features:

1. JSX

JSX means JavaScript XML. It is an extension of JS language syntax. It provides a way to render components using a syntax similar to HTML. It uses JSX to write its components. It can use pure JavaScript also but prefers JSX. Babel uses it, a pre-processor, to convert text similar to HTML found in JavaScript files into standard JS objects. The HTML code can be embedded in JavaScript to make HTML code more easily understandable, enhance the performance of JavaScript, and make the application robust.

2. Virtual Document Object Model

React make an in-memory data structure cache, then it computes the difference between the previous DOM and the new one and then updates the changes or mutations performed. Thus, it updates only the changes, not the whole application. This helps to increase speed and performance and reduces memory wastage.

3. Testability

React views are used as the state’s functions where the state determines the behavior of the component. Therefore we can make changes to the state and then pass it to a view the ReactJS and then determine the output and the actions, functions, and events. This makes testing and debugging easy.

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4. SSR

It stands for Server- Side Rendering. It permits to pre-render the initial state of the components at the server-side. The browser can render without waiting for all the JavaScript to be executed or loaded. This makes web pages to load faster. It helps the user to view the web pages even when React is still downloading the JavaScript, linking events or creating virtual DOM at the backend.

5. One Way Data Binding

It allows one-way flow of data, i.e. one-way data binding. Due to this feature, there is better control over the application. It makes the application’s state to be contained in specific stores, and therefore all other components remain loosely coupled. This enhances the flexibility and efficiency of the application.

6. Simplicity

JSX files make the application simple and understandable. Standard JavaScript can be used to code, but the usage of JSX makes it easier. Several lifecycle methods and its component-based approach make it simpler to learn and execute.

7. Learning Curve

In comparison to other frameworks, the learning curve of React is low. Beginners having basic programming language can also learn to React easily.

How does it Work?

When the developer team of Facebook was building client-side apps, it found that the Document Object Model (DOM) is slow. In order to make it faster, a virtual DOM, which is a tree representation of DOM in JavaScript, is implemented in it.
It operates on Virtual DOM. It does not manipulate the document on the browser after the changes are made; it makes changes on the virtual DOM. When the virtual DOM is completely updated, then it updates the browser’s DOM in the most efficient way possible.
The virtual DOM of React resides entirely in memory. It represents the web browser’s DOM, so when a React component is written, a virtual component that is cheap to create is made, which is turned into DOM by React. It was made to be used in the browser, but with Node.js, it can be used with the server also.

How do we Use it?

Using React is simple as including a JS file in HTML.

Let us see the usage of React by a simple example.

Code:

<html>
<head>
<meta charset = "utf-8">
<title> First React Code</title>
<script src = "https://cdnjs.cloudfare.com/ajax/libs/react/15.3.1/react.min.js"> </script>
<script src = "https://cdnjs.cloudfare.com/ajax/libs/react/15.3.1/react-dom.min.js"> </script>
<script src = "https://unpkg.com/babel-standalone@6/babel.min.js"> </script>
</head>
<body>
<div id= "application"> </div>
<script type = "text/babel">
ReactDOM. render(<h2> First Code </h2>, document. querySelector ('#application')
);
</script>
</body>
</html>

It seems a bit difficult, but it is easy to implement and learn.

Who Uses React?

It is becoming popular in today’s market, and its features are helping big companies in improving their experience and interfaces.
Internet giants like Facebook, Instagram, Netflix, New York Times, Yahoo Mail, Khan Academy, WhatsApp, Vivaldi Browser, Codecademy, and Dropbox are using React in one or the another way. Sberbank of Russia has also used React o develop their bank’s website.
Many websites like github.com, reddit.com, outlook.live.com, bitbucket.org, account.godaddy.com, and many more also use React.

Advantages and Disadvantages

Given below are the advantages and disadvantages:

Advantages

SEO friendly
It is easy to create test cases for UI
React components can be reused easily
Ensures faster rendering
Debugging is easy
Ease of migration
Enhances productivity
Writing components is easy
Stable code
Has a helpful developer toolset
It is available for mobile app development
Easy to learn
Enhances performance

Disadvantages

The high pace of development
Poor documentation
Additional SEO hassle
View-oriented only
Large size library
The learning curve for beginners
Requires manual processing of data changes
I need more code in some cases

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