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Test Info: Warnings
- This test has a WPT meta file that expects 1 subtest issues.
- This WPT test may be referenced by the following Test IDs:
- /intersection-observer/v2/delay-test.html - WPT Dashboard Interop Dashboard
<!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>
body, html {
margin: 0;
}
pre, #log {
position: absolute;
top: 0;
left: 200px;
}
#target {
width: 100px;
height: 100px;
background-color: green;
}
#occluder {
width: 100px;
height: 100px;
background-color: blue;
}
</style>
<div id="target"></div>
<div id="occluder"></div>
<script>
async_test(t => {
let entries = [];
let delay = 100;
let target = document.getElementById("target");
let occluder = document.getElementById("occluder");
assert_true(!!target, "target exists");
assert_true(!!occluder, "occluder exists");
let observer = new IntersectionObserver(function(changes) {
entries = entries.concat(changes)
}, {trackVisibility: true, delay: delay});
observer.observe(target);
entries = entries.concat(observer.takeRecords());
assert_equals(entries.length, 0, "No initial notifications.");
// The first notification should be sent without delay.
waitForNotification(t, t.step_func(step0));
function waitForDelay(timerExpiredBeforeLastFrame, nextStep) {
requestAnimationFrame(t.step_func(() => {
if (timerExpiredBeforeLastFrame) {
// New notifications should have been generated during the previous
// frame and delivered by now.
assert_equals(entries.length, 2);
assert_greater_than(entries[1].time - entries[0].time, delay);
assert_false(entries[1].isVisible);
nextStep();
} else {
// Observer may not have updated yet. Wait for next frame.
let timerExpired = performance.now() - entries[0].time >= delay;
waitForDelay(timerExpired, nextStep);
}
}));
}
function step0() {
assert_equals(entries.length, 1);
assert_true(entries[0].isVisible);
// This should trigger a notification on the next run.
occluder.style.marginTop = "-10px";
// Enter a rAF loop until the delay timer expires.
waitForDelay(false, step1);
}
function step1() {
occluder.style.marginTop = "10px";
// This style invalidation should cause a frame to run before the observer
// can generate a notification (due to delay parameter). Make sure the
// notification will still be generated even if we don't force more frames
// with a rAF loop.
t.step_timeout(() => {
assert_equals(entries.length, 3);
assert_true(entries[0].isVisible);
t.done();
}, 2 * delay);
}
}, "'delay' parameter throttles frequency of notifications.");
</script>