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Test Info:

<!DOCTYPE HTML>
<html>
<!--
-->
<head>
<meta charset="utf-8">
<title>Test for Bug 886646</title>
<script src="/tests/SimpleTest/SimpleTest.js"></script>
<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
<style type="text/css">
#scroller {
width: 100px;
height: 100px;
padding: 10px;
border: 10px solid black;
margin: 10px;
overflow: hidden;
}
#container {
width: 50px;
height: 50px;
}
#sticky {
position: sticky;
width: 10px;
height: 10px;
overflow: hidden;
}
</style>
</head>
<body>
<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=886646">Mozilla Bug 886646</a>
<div id="display">
<div id="scroller">
<div id="container">
<div id="sticky"></div>
</div>
</div>
</div>
<pre id="test">
<script type="application/javascript">
/** Test for Bug 886646 - Offsets for sticky positioning, when accessed through
* getComputedStyle(), should be accurately computed. In particular,
* percentage offsets should be computed in terms of the scroll container's
* content box. */
// Test that percentage sticky offsets are computed in terms of the
// scroll container's content box
var offsets = {
"top": 10,
"left": 20,
"bottom": 30,
"right": 40,
};
var scroller = document.getElementById("scroller");
var container = document.getElementById("container");
var sticky = document.getElementById("sticky");
var cs = getComputedStyle(sticky, "");
for (var prop in offsets) {
sticky.style[prop] = offsets[prop] + "%";
is(cs[prop], offsets[prop] + "px");
}
// ... even in the presence of scrollbars
scroller.style.overflow = "scroll";
container.style.width = "100%";
container.style.height = "100%";
var ccs = getComputedStyle(container, "");
function isApproximatelyEqual(a, b) {
return Math.abs(a - b) < 0.001;
}
for (var prop in offsets) {
sticky.style[prop] = offsets[prop] + "%";
var basis = parseFloat(ccs[prop == "left" || prop == "right" ?
"width" : "height"]) / 100;
ok(isApproximatelyEqual(parseFloat(cs[prop]), offsets[prop] * basis));
}
</script>
</pre>
</body>
</html>