JSFiddle - React, Tailwind, and code Playground

HTML

<div>hogehoige</div>

CSS

.hoge{color:red;}

JavaScript

/*!
 * stuQuery v1.0.10
 */
// I don't like to pollute the global namespace 
// but I can't get this to work any other way.
var eventcache = {};
function S(e){
	function querySelector(els,selector){
		var result = new Array();
		var a,els2,i,j,k,tmp;
		if(selector.indexOf(':eq') >= 0){
			a = selector.split(' ');
			for(i = 0; i < a.length; i++){
				if(i==0){
					tmp = getBy(els,a[i]);
				}else{
					els2 = new Array();
					for(j = 0; j < tmp.length; j++) els2 = els2.concat(getBy(tmp[j],a[i]));
					tmp = els2.splice(0);
				}
			}
		}else tmp = els.querySelectorAll(selector);					// We can use the built-in selector
		for(k = 0; k < tmp.length; k++){ result.push(tmp[k]); }
		return result;
	}
	function getBy(e,s){
		var i = -1;
		var result = new Array();
		if(s.indexOf(':eq') > 0){
			var m = s.replace(/(.*)\:eq\(([0-9]+)\)/,'$1 $2').split(" ");
			s = m[0];
			i = parseInt(m[1]);
		}
		if(s[0] == '.') els = e.getElementsByClassName(s.substr(1));
		else if(s[0] == '#') els = e.getElementById(s.substr(1));
		else els = e.getElementsByTagName(s);
		if(!els) els = [];
		// If it is a select field we don't want to select the options within it
		if(els.nodeName && els.nodeName=="SELECT") result.push(els);
		else{
			if(typeof els.length!=="number") els = [els];
			for(k = 0; k < els.length; k++){ result.push(els[k]); }
			if(i >= 0 && result.length > 0){
				if(i < result.length) result = [result[i]];
				else result = [];
			}
		}
		return result;
	}
	function matchSelector(e,s){
		var result = false;
		// Does this one element match the s
		if(s[0] == '.'){
			s = s.substr(1);
			for(var i = 0; i < e.classList.length; i++) if(e.classList[i] == s) return true;
		}else if(s[0] == '#'){
			if(e.id == s.substr(1)) return true;
		}else{
			if(e.tagName == s.toUpperCase()) return true;
		}
		return false;
	}
	function stuQuery(els){
		// Make our own fake, tiny, version of jQuery simulating the parts we need
		var elements;
		if(typeof els==="string") this.e =...