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<!DOCTYPE html>
<head>
<title>Images with loading='lazy' load when in the viewport</title>
<link rel="author" title="Chris Harrelson" href="mailto:chrishtr@chromium.org">
<link rel="help" href="https://github.com/scott-little/lazyload">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
</head>
<script>
const t = async_test("Test that images with loading='lazy' under multicol load once they enter the viewport.");
let has_in_viewport_loaded = false;
let has_window_loaded = false;
const in_viewport_img_onload = t.step_func(function() {
assert_false(has_in_viewport_loaded, "The in_viewport element should load only once.");
has_in_viewport_loaded = true;
});
window.addEventListener("load", t.step_func_done(function() {
assert_true(has_in_viewport_loaded, "The in_viewport element should have loaded before window.load().");
assert_false(has_window_loaded, "The window.load() event should only fire once.");
has_window_loaded = true;
}));
</script>
<div class=texty style="column-count: 2; height: 300px">
<div style="border: 1px solid black">
<h2 style="column-span: all"></h2>
<img loading="lazy" src="resources/image.png?first" width="160" height="120"
onload="in_viewport_img_onload()">
</div>
</div>
<!--
This async script loads very slowly in order to ensure that, if the
below_viewport element has started loading, it has a chance to finish
loading before window.load() happens, so that the test will dependably fail
in that case instead of potentially passing depending on how long different
resource fetches take.
-->
<script async src="/common/slow.py"></script>
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