<!DOCTYPE html>
<html>
<head>
<style>

#target {
    position: absolute;
    left: 0;
    top: 0;
    width: 100px;
    height: 100px;
    background-color: black;
    will-change: transform;
}

</style>
</head>
<body>
<div id="target"></div>
<script>

if (window.testRunner)
    testRunner.waitUntilDone();

const animation = document.getElementById("target").animate({ transform: ["translateX(50px)", "translateX(100px)"] }, 1000);

// Wait until the animation is ready which means the action to play an accelerated animation has been enqueued by now, but not commmitted.
animation.ready.then(() => {
    // Cancel the animation, this should cancel the uncommitted accelerated animation.
    animation.cancel();
    if (window.testRunner)
        testRunner.notifyDone();
});

</script>
</body>
</html>