What is React.js?

What is React.js?

React is a free and open-source front-end JavaScript library for building user interfaces based on UI components. It is maintained by Meta and a community of individual developers and companies. The role of React JS is to handle the data layer for web and mobile apps. It also allows you to formulate the reusable components of UI. React allows creating large web applications that can modify the data without reloading the entire page to the Developers. React generates astonishing results with other JavaScript libraries or frameworks that may include Angular JS. The main purpose of React is to be fast, scalable, and simple. It works only on user interfaces in the application. This corresponds to the view in the MVC template. It can be used with a combination of other JavaScript libraries or frameworks, such as Angular JS in MVC.

React.js Features

  • React.js is declarative
  • React.js is simple
  • React.js is component based
  • React.js supports server side
  • React.js is extensive
  • React.js is fast
  • React.js is easy to learn

JSX

In React, instead of using regular JavaScript for templating, it uses JSX. JSX is a simple JavaScript that allows HTML quoting and uses these HTML tag syntax to render subcomponents. HTML syntax is processed into JavaScript calls of React Framework. We can also write in pure old JavaScript.
  • Instead of putting JavaScript into HTML, JSX allows us to put HTML into JavaScript,
  • JSX stands for JavaScript XML.
  • It is simply a syntax extension of React.
  • It allows us to directly write HTML in React.
const htmlElement = <h1>Hello World</h1>

Single-Way data flow

In React, a set of immutable values are passed to the components renderer as properties in its HTML tags. The component cannot directly modify any properties but can pass a call back function with the help of which we can do modifications. This complete process is known as “properties flow down; actions flow up”.

Virtual Document Object Model

React creates an in-memory data structure cache which computes the changes made and then updates the browser. This allows a special feature that enables the programmer to code as if the whole page is rendered on each change whereas react library only renders components that actually change.

Why React.js?

Now, the main question arises in front of us is why one should use React. There are so many open-source platforms for making the front-end web application development easier, like Angular. Let us take a quick look on the benefits of React over other competitive technologies or frameworks. With the front-end world-changing on a daily basis, it’s hard to devote time to learning a new framework – especially when that framework could ultimately become a dead end. So, if you're looking for the next best thing but you're feeling a little bit lost in the framework jungle, I suggest checking out React.
1. Simplicity
2. Easy to learn
3. Native Approach
4. Data Binding
5. Performance 
6. Testability 

How to create a React app?

There are two ways to create React apps. First, you use npm (Node Package Manager) installed on your machine. If you’re using VS Code, you need to make sure you’ve configured your machine to run React code in VS code using npm. You will also need to setup a build environment for React that typically involved use of npm (node package manager), webpack, and Babel.
// Create React app
npx create-react-app my-app

cd my-app

npm start
We can also create a React app without npm by directly importing React.js library in our HTML code. This is exactly what we will do here.

Companies using React.js

Netflix, Airbnb, Instagram, and the New York Times, to name a few.
React brings many advantages to the table, making it a better choice than other frameworks like Angular.js.
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