JSFiddle - React, Tailwind, and code Playground

JavaScript

Object.defineProperty(HTMLElement.prototype, 'customObject',
{ configurable: true, enumerable: true, writeable: true, value: {} });

var e = document.createElement('div');
e.customObject.prop = "bla";
alert(e.customObject.prop);
var d = document.createElement('div');
alert(d.customObject.prop);