JSFiddle - React, Tailwind, and code Playground

HTML

<intelligent-bee></intelligent-bee>

JavaScript

var beePrototype = Object.create(HTMLElement.prototype);
beePrototype.createdCallback = function(){
    this.innerHTML = "I am an intelligentbee";
}
beePrototype.sayHi = function(){
    alert("buzz");
}

document.registerElement("intelligent-bee", {prototype: beePrototype});

var IB = document.querySelector("intelligent-bee");
IB.sayHi();