JSFiddle - React, Tailwind, and code Playground

HTML

<div id="result">
</div>

JavaScript

function MyObject()
{
	return {
  	key: "value",
    hello: function() { console.log('world'); }
  }
}

var obj = new MyObject();

document.getElementById('result').innerHTML = 
	'<b>obj</b> <i>instanceof</i> <b>MyObject</b>: ' + (obj instanceof MyObject ? 'true' : 'false')