<!DOCTYPE html>
<title>Mutating the 'begin' attribute after the element has started</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<svg>
  <rect width="100" height="100" fill="blue">
    <animate id="anim" attributeName="x" values="100; 0"
             begin="0s" dur="50ms" fill="freeze"/>
  </rect>
</svg>
<script>
  async_test(function(t) {
    let anim = document.getElementById("anim");
    anim.endEventsReceived = 0;
    anim.addEventListener('endEvent', t.step_func(function() {
      anim.endEventsReceived++;
      if (anim.endEventsReceived)
        t.done();
    }));
    onload = function() {
      // Allow some time to pass before mutating 'begin'. This should ensure
      // that the element has started.
      requestAnimationFrame(function() {
        anim.ownerSVGElement.setCurrentTime(0);
        anim.setAttribute("begin", "50ms");
      });
    };
  });
</script>
