React Js : React. js is an open-source JavaScript library that is used for building user interfaces specifically for single-page applications. It's used for handling the view layer for web and mobile apps. React also allows us to create reusable UI components
React Features :
It is playing an essential role in the front-end ecosystem.
The important features of ReactJS are as following.

JSX
Components
uni-directional data flow or One-way data binding.
It uses the virtual DOM instead of the real DOM.
Simplicity
Performance

advantages of React Js Ad & Dis Deep
It increases the application’s performance
It can be conveniently used on the client as well as server side
Because of JSX, code’s readability increases
React is easy to integrate with other frameworks like Meteor, Angular, etc
Using React, writing UI test cases become extremely easy

Disadvantage of ReactJS :
The high pace of development.
The high pace of development has an advantage and disadvantage both. ...
Poor Documentation.
View Part.
JSX as a barrier.