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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);
}
#target {
width: 100px;
height: 100px;
background-color: green;
}
</style>
<div class="spacer"></div>
<div id="target"></div>
<div class="spacer"></div>
<script>
var entries = [];
runTestCycle(function() {
var target = document.getElementById("target");
assert_true(!!target, "Target exists");
function createObserver() {
new IntersectionObserver(function(changes) {
entries = entries.concat(changes)
}).observe(target);
}
createObserver();
runTestCycle(step0, "First rAF");
}, "IntersectionObserver that is unreachable in js should still generate notifications.");
function step0() {
document.scrollingElement.scrollTop = 300;
runTestCycle(step1, "document.scrollingElement.scrollTop = 300");
assert_equals(entries.length, 1, "One notification.");
}
function step1() {
document.scrollingElement.scrollTop = 0;
assert_equals(entries.length, 2, "Two notifications.");
}
</script>