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<!doctype html>
<meta name="viewport" content="width=device-width,initial-scale=1">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
<link rel="author" title="Mozilla" href="https://mozilla.org">
<link rel="help" href="https://w3c.github.io/IntersectionObserver/#dom-intersectionobserver-rootmargin">
<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1553673">
<style>
html { width: 100vw; height: 100vh }
</style>
<script>
const t = async_test("IntersectionObserver root margin cannot end up with negative rect (and thus non-intersecting) due to rounding");
let remainingTests = 100;
// This is just a best-effort test to catch issues.
for (let i = 0; i < 100; ++i) {
let offset = i / 100;
let observer;
observer = new IntersectionObserver(t.step_func(function(entries) {
assert_equals(entries.length, 1);
assert_equals(entries[0].target, document.documentElement);
assert_true(entries[0].isIntersecting, "should be intersecting at " + offset);
if (!--remainingTests)
t.done();
observer.disconnect();
}), { rootMargin: `${-100 * (1 - offset)}% 0px ${-100 * offset}%` });
observer.observe(document.documentElement);
}
</script>
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