JSFiddle - React, Tailwind, and code Playground

HTML

<div class="test"></div>

JavaScript

String.prototype.trim = function() {

    return this.replace(/(^\s+)|(\s+$)/g, "");
};

function $(selector, elem) {
  
    selector = selector.trim();

	var selects = (elem || document).querySelectorAll(selector);

	return selects.length  == 1 ? selects[0]:  selects;
}

var test = $(".test");

[].forEach.call(test, function (item, i) {

    item.innerHTML =  i;
});