A user interface framework written in javascript.
It is used both for websites, and for mobile applications.
It is also referred to as react.js

Documentation

homepage https://reactjs.org/

api docs https://reactjs.org/docs/react-api.html

codepen (interactive editor) https://codepen.io/pen

Basics

react environments

react anatomy

react components

react elements

react fragments

homepage	https://reactjs.org/
api docs	https://reactjs.org/docs/react-api.html
codepen (interactive editor)	https://codepen.io/pen