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image-loading-lazy-in-viewport-dynamic.tentative.html
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image-loading-lazy-in-viewport-dynamic.tentative.html
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<!DOCTYPE html>
<head>
<title>In viewport images with loading='lazy' and changed to loading='eager'
do not block the window load event</title>
<link rel="author" title="Rob Buis" href="mailto:rbuis@igalia.com">
<link rel="help" href="https://github.com/scott-little/lazyload">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
</head>
<!--
Marked as tentative until https://github.com/whatwg/html/pull/3752 is landed.
-->
<script>
const t = async_test("Test that in viewport images with loading='lazy' and " +
"changed to loading='eager' do not block the window " +
"load event.");
let has_in_viewport_loaded = false;
let has_window_loaded = false;
const in_viewport_img_onload = t.step_func_done(function() {
assert_false(has_in_viewport_loaded,
"The in_viewport element should load only once.");
assert_true(has_window_loaded,
"The window.load() event should fire before in_viewport image loads.");
has_in_viewport_loaded = true;
});
window.addEventListener("load", t.step_func(function() {
assert_false(has_window_loaded,
"The window.load() event should only fire once.");
has_window_loaded = true;
}));
</script>
<body>
<img id="in_viewport" src="resources/image.png?pipe=trickle(d2)"
loading="lazy" onload="in_viewport_img_onload();">
<script>
document.getElementById("in_viewport").loading = 'eager';
</script>
</body>