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<!doctype html>
<meta charset="utf-8">
<title>Overflow: intersection observer with overflow-clip-margin</title>
<link rel="help" href="https://www.w3.org/TR/css-overflow-3/#propdef-overflow-clip-margin">
<link rel="author" title="Scott Violet" href="mailto:sky@chromium.org">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
#clipped_container {
overflow: clip;
width: 100px;
height: 100px;
border: solid;
overflow-clip-margin: 50px;
}
#big_green_div {
position: relative;
width: 1000px;
height: 1000px;
background: green;
left: -200px;
top: -200px;
}
/* These values ensure the element is vertically offscreen. */
.spacer { width: 150px; height: calc(100vh + 10px); }
</style>
<div class="spacer"></div>
<div id="clipped_container">
<div id="big_green_div"></div>
</div>
<script>
let t = async_test("ParentWithOverflowClipMargin");
let options = {
threshold: 0,
rootMargin: '0px'
}
// The 'big_green_div' is initially on screen due to
// overflow-clip-margin of the parent. Once the observer is notified, the
// overflow-clip-margin is reduced so that 'big_green_div' is no longer
// on screen, and the observer should again be notified.
let gotIntersects = false;
let intersectionObserver = new IntersectionObserver((entries, observer) => {
t.step(function() { assert_equals(1, entries.length); });
let entry = entries[0];
if (!gotIntersects) {
t.step(function() { assert_true(entry.isIntersecting); });
gotIntersects = true;
document.getElementById('clipped_container').style.overflowClipMargin = "0px";
} else {
t.step(function() { assert_false(entry.isIntersecting); });
t.done();
}}, options);
intersectionObserver.observe(document.getElementById('big_green_div'));
</script>
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