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<!doctype html>
<title>Visual Viewport Scroll Event Order</title>
<meta charset=utf-8>
<link rel="help" href="https://wicg.github.io/visual-viewport/index.html">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/testdriver.js"></script>
<script src="/resources/testdriver-actions.js"></script>
<script src="/resources/testdriver-vendor.js"></script>
<script src="viewport_support.js"></script>
<style>
#target {
width: 100px;
height: 100px;
background-color: red;
position: absolute;
top: 300vh;
}
#scroller1,#scroller2 {
width: 200px;
height: 200px;
overflow: auto;
}
#spacer {
width: 80px;
height: 1000px;
background-image: linear-gradient(45deg, #808080 25%, transparent 25%),
linear-gradient(-45deg, #808080 25%, transparent 25%),
linear-gradient(45deg, transparent 75%, #808080 75%),
linear-gradient(-45deg, transparent 75%, #808080 75%);
background-size: 40px 40px;
background-position: 0 0, 0 20px, 20px -20px, -20px 0px;
}
</style>
<body>
<div id="target"></div>
<div id="scroller1"><div id="spacer"></div></div>
<div id="scroller2"><div id="spacer"></div></div>
</body>
<script>
async function oneRaf() {
return new Promise((resolve) => {
window.requestAnimationFrame(resolve);
});
}
const scroller1 = document.getElementById('scroller1');
const scroller2 = document.getElementById('scroller2');
promise_test(async t => {
// Pinch-zoom in so that the scrollIntoView call below causes scrolling in
// both the layout and visual viewports within the same rAF.
await pinchZoomIn();
assert_greater_than(window.visualViewport.scale, 1, 'Must have zoomed in');
await oneRaf();
const scroll_events = [];
// Register the scroll handlers on the window, visualViewport, and both
// <div> scrollers.
{
window.onscroll = () => { scroll_events.push('window-attribute'); }
window.addEventListener('scroll', () => { scroll_events.push('window-addEventListener'); });
window.visualViewport.onscroll = () => { scroll_events.push('visualViewport-attribute'); }
window.visualViewport.addEventListener('scroll', () => {
scroll_events.push('visualViewport-addEventListener'); });
scroller1.addEventListener('scroll',
() => { scroll_events.push('scroller1'); });
scroller2.addEventListener('scroll',
() => { scroll_events.push('scroller2'); });
}
// Cause scrolling in each scroller and scrollIntoView so that the layout
// and visual viewports both scroll.
scroller1.scrollTop = 200;
document.getElementById('target').scrollIntoView();
scroller2.scrollTop = 200;
// Wait a rAF since scroll events are delievered as part of the event loop.
await oneRaf();
// The scroll events must be delivered in the order they were executed,
// scroller1 first, then the viewport (window then visualViewport), then
// scroller2.
assert_equals(scroll_events.toString(),
'scroller1,' +
'window-attribute,window-addEventListener,' +
'visualViewport-attribute,visualViewport-addEventListener,' +
'scroller2');
}, "Scroll event ordering");
</script>
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