JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
<div id="child" class="child">

</div>
</div>

JavaScript

function matchesSelector(el, selector) {
	var p = Element.prototype;
	var f = p.matches || p.webkitMatchesSelector || p.mozMatchesSelector || p.msMatchesSelector || function(s) {
		return [].indexOf.call(this.parentNode.querySelectorAll(s), this) !== -1;
	};
	return f.call(el, selector);
}

var el = document.getElementById('child'),
    selector = 'body > #container .child';

el.innerHTML += 'matches ' + selector + ': ' + matchesSelector(el, selector);