<!DOCTYPE html>
<head>
<title>Below viewport images with loading='lazy' and changed to
loading='eager' load and do not block the window load event</title>
<link rel="author" title="Rob Buis" href="mailto:[email protected]">
<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 below viewport images with loading='lazy' " +
"and changed to loading='eager' load and do not block " +
"the window load event.");
let has_below_viewport_loaded = false;
let has_window_loaded = false;
window.addEventListener("load", t.step_func(function() {
assert_false(has_window_loaded,
"The window load event should only fire once.");
has_window_loaded = true;
}));
const below_viewport_img_onload = t.step_func_done(function() {
assert_false(has_below_viewport_loaded,
"The in_viewport element should load only once.");
assert_true(has_window_loaded,
"The window load event should have fired before " +
"below_viewport loaded.");
has_below_viewport_loaded = true;
});
</script>
<body>
<div style="height:10000px;"></div>
<img id="below_viewport" src="resources/image.png?below-viewport-dynamic&pipe=trickle(d2)"
loading="lazy" onload="below_viewport_img_onload();">
<script>
assert_false(has_window_loaded,
"The window load event should not fire before " +
"changing below_viewport to loading='eager'.");
document.getElementById("below_viewport").loading = 'eager';
</script>
</body>
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