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Test Info:
- This WPT test may be referenced by the following Test IDs:
- /css/css-scroll-anchoring/heuristic-with-offset-update-from-scroll-event-listener.html - WPT Dashboard Interop Dashboard
<!doctype html>
<meta charset="utf-8">
<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
#scroller {
overflow: scroll;
height: 500px;
height: 500px;
}
#before {
height: 200px;
}
#anchor {
position: relative;
width: 200px;
height: 200px;
margin-bottom: 500px;
background-color: blue;
top: 0px;
}
</style>
<div id="scroller">
<div id="before">
</div>
<div id="anchor">
</div>
</div>
<script>
async_test(t => {
let scroller = document.querySelector('#scroller');
let before = document.querySelector('#before');
let anchor = document.querySelector('#anchor');
scroller.onscroll = t.step_func(function() {
// Adjust the 'top' of #anchor, which should trigger a suppression
anchor.style.top = '10px';
// Expand #before and make sure we don't apply an adjustment
before.style.height = '300px';
assert_equals(scroller.scrollTop, 200);
t.step_timeout(t.step_func_done(function() {
// Expand #before again and make sure we don't keep #anchor as
// an anchor from the last time.
before.style.height = '600px';
assert_equals(scroller.scrollTop, 200);
}), 0);
});
// Scroll down to select #anchor as a scroll anchor
scroller.scrollTop = 200;
}, 'Positioned ancestors with dynamic changes to offsets trigger scroll suppressions.');
</script>