test_animations_dynamic_changes.html

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<!DOCTYPE HTML>

<html>

<!--

https://bugzilla.mozilla.org/show_bug.cgi?id=978833

-->

<head>

  <title>Test for Bug 978833</title>

  <script src="/tests/SimpleTest/SimpleTest.js"></script>

  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>

  <style id="style">

  @keyframes a {

    from, to {

      /* a non-inherited property, so it's cached in the rule tree */

      margin-left: 50px;

  .alwaysa {

    animation: a linear 1s infinite;

  </style>

</head>

<body>

<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=978833">Mozilla Bug 978833</a>

<p id="display"></p>

<pre id="test">

<script type="application/javascript">

var p = document.getElementById("display");

var cs = getComputedStyle(p, "");

var style = document.getElementById("style").sheet;

/** Test for Bug 978833 **/

function test_bug978833() {

  var kfs = style.cssRules[0];

  var kf = kfs.cssRules[0];

  is(kf.style.marginLeft, "50px", "we found the right keyframe rule");

  p.classList.add("alwaysa");

  is(cs.marginLeft, "50px", "p margin-left should be 50px");

  // Temporarily remove the animation style, since we resolve keyframes

  // on top of current animation styles (although maybe we shouldn't),

  // so we need to remove those styles to hit the rule tree cache.

  p.classList.remove("alwaysa");

  is(cs.marginLeft, "0px", "p margin-left should be 0px without animation");

  p.classList.add("alwaysa");

  kf.style.marginLeft = "100px";

  is(cs.marginLeft, "100px", "p margin-left should be 100px after change");

  // Try the same thing a second time, just to make sure it works again.

  p.classList.remove("alwaysa");

  is(cs.marginLeft, "0px", "p margin-left should be 0px without animation");

  p.classList.add("alwaysa");

  kf.style.marginLeft = "150px";

  is(cs.marginLeft, "150px", "p margin-left should be 150px after second change");

  p.style.animation = "";

test_bug978833();

</script>

</pre>

</body>

</html>