<!doctype html>
<style>
* {
margin: 0px;
background-color: red;
}
#box {
width: 100px;
height: 100px;
background-color: blue;
animation: flash 1s steps(1, end) 4;
}
@keyframes flash {
0% { opacity: 1; }
50% { opacity: 0; }
100% { opacity: 1; }
}
</style>
<div id="box"></div>
<script>
var baseTime = Date.now();
var box = document.getElementById("box");
box.addEventListener("animationstart", onAnimationEvent, false);
box.addEventListener("animationiteration", onAnimationEvent, false);
box.addEventListener("animationend", onAnimationEvent, false);
function onAnimationEvent(event) {
console.log(`Event [${event.type}]`
+ ` at ${event.elapsedTime} sec`);
}
</script>