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Test Info:

<!DOCTYPE html>
<meta name="viewport" content="width=device-width,initial-scale=1">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="./resources/intersection-observer-test-utils.js"></script>
<style>
pre, #log {
position: absolute;
top: 0;
left: 200px;
}
.spacer {
height: calc(100vh + 100px);
}
</style>
<div class="spacer"></div>
<br id="target">
<div class="spacer"></div>
<script>
var vw = document.documentElement.clientWidth;
var vh = document.documentElement.clientHeight;
var entries = [];
var target;
var tw, th;
runTestCycle(function() {
target = document.getElementById("target");
let target_rect = target.getBoundingClientRect();
tw = target_rect.width;
th = target_rect.height;
assert_true(!!target, "target exists");
var observer = new IntersectionObserver(function(changes) {
entries = entries.concat(changes)
});
observer.observe(target);
entries = entries.concat(observer.takeRecords());
assert_equals(entries.length, 0, "No initial notifications.");
runTestCycle(step0, "First rAF.");
}, "IntersectionObserver observing a br element.");
function step0() {
document.scrollingElement.scrollTop = 300;
runTestCycle(step1, "document.scrollingElement.scrollTop = 300");
// The numbers in brackets are target client rect; intersection rect;
// and root bounds.
checkLastEntry(entries, 0, [8, 8 + tw, vh + 108, vh + 108 + th, 0, 0, 0, 0, 0, vw, 0, vh, false]);
}
function step1() {
document.scrollingElement.scrollTop = 100;
runTestCycle(step2, "document.scrollingElement.scrollTop = 100");
checkLastEntry(entries, 1, [8, 8 + tw, vh - 192, vh - 192 + th, 8, 8 + tw, vh - 192, vh - 192 + th, 0, vw, 0, vh, true]);
}
function step2() {
document.scrollingElement.scrollTop = 0;
checkLastEntry(entries, 2, [8, 8 + tw, vh + 8, vh + 8 + th, 0, 0, 0, 0, 0, vw, 0, vh, false]);
}
</script>