JSFiddle - React, Tailwind, and code Playground

HTML

<script>

;(function () {
    var createElement = document.createElement;
    var pendingGaRequests = 0;
    var gaUrl = /www[.]google-analytics[.]com/i;
    var onComplete;

    function addEvent(elem, evnt, func)
    {
        if (elem.addEventListener) {
            elem.addEventListener(evnt, func, false);
        } else if (elem.attachEvent) {
            elem.attachEvent('on' + evnt, func);
        } else {
            elem['on' + evnt] = func;
        }
    }

    function removeEvent(elem, evnt, func)
    {
        if (elem.removeEventListener) {
            elem.removeEventListener(evnt, func, false);
        } else if (elem.detachEvent) {
            elem.detachEvent('on' + evnt, func);
        } else {
            elem['on' + evnt] = null;
        }
    }

    function addSrcChangeEvent(elem, callback)
    {
        function listen(listElem)
        {
            pendingGaRequests += 1;
            addEvent(listElem, 'error', callback);
            addEvent(listElem, 'load', callback);
        }

        var MutationObserverReal = window.MutationObserver || window.WebKitMutationObserver || false;
        if (!!MutationObserverReal) {
            elem._observer = new MutationObserverReal(function (mutations) {
                mutations.forEach(function (mutation) {
                    if (mutation.attributeName == 'src' && gaUrl.test(mutation.target.src)) {
                        listen(mutation.target);
                    }
                });
            });

            elem._observer.observe(elem, {
                attributes: true,
                childList: false,
                characterData: false
            });
        } else if (elem.addEventListener) {
            elem._DOMAttrModified = function (e) {
                if (e.attrName == 'src' && gaUrl.test(e.target.src)) {
                    listen(e.target);
                }
            };
            elem.addEventListener('DOMAttrModified', elem._DOMAttrModified);
        } else if...