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              <button id="abutton" onClick="this.classList.toggle('uploaded')">Click Me</button>

<br />
<p>Click on button above to see transitionend event in action, alerting a message at the end of the animation.</p>

<p><b style="color:red">Note:</b> In IE (as of IE Edge), the transitionend event doesn't fire when a psuedo element is being transitioned, rather than on the element itself. Due to this, IE users will not see an alert message. :(

<p style="position:absolute;bottom:10px">From tutorial <a href="http://www.javascriptkit.com/javatutors/css-transition-functions.shtml" target="_new">Four Essential JavaScript functions to tame CSS3 Transitions and Animations</a>
	width: 200px;
	border-radius: 5px;
	padding: 10px;
	background: #eee;
	font-weight: bold;
	position: relative;
	text-align: center;
	font-size: 110%;
	overflow: hidden;
	border: 1px solid gray;
	cursor: pointer;
	text-transform: uppercase;

	content: '';
	position: absolute;
	left: 0;
	bottom: 0;
	width: 0;
	height: 6px;
	background: green;
	transition: all .5s;

	width: 100%;
              var abutton = document.getElementById('abutton')

function gettransitionend(){
	var root = document.documentElement
	var transitions = {
	for (var t in transitions){
		if (root.style[t] !== undefined ){
			return transitions[t];
	return undefined

//Example Usage:
var transitionendevt = gettransitionend()
if (transitionendevt){ // if transitionend event supported by browser
	abutton.addEventListener(transitionendevt, function(e){
		var isuploaded = this.classList.contains('uploaded')
		alert(isuploaded? 'File Uploaded' : 'File Unloaded')	
	}, false)
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