What is ReactJS?

React or ReactJS is the most popular library in the Front end world. React is used to create a single page application(SPA).

React js a JavaScript library to build a User Interface as more interactive. React was developed by the Facebook community in 2013. React is using one-way data binding. It's a unidirectional data flow and react is using virtual DOM concept, Virtual DOM is rendering the data faster than Real DOM 

React is handing View part of MVC pattern