<!DOCTYPE html>
<head>
<title>Multiple queued lazy load navigations do not crash the page</title>
<link rel="author" title="Dom Farolino" href="mailto:[email protected]">
<link rel="help" href="https://html.spec.whatwg.org/multipage/urls-and-fetching.html#lazy-loading-attributes">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
</head>
<script>
const t = async_test('Multiple queued lazy load navigations do not crash ' +
'the page');
let has_below_viewport_loaded = false;
window.addEventListener("load", t.step_func(() => {
assert_false(has_below_viewport_loaded,
"The below_viewport element should not have loaded before " +
"window.load().");
// Queue another lazy load navigation on the iframe. This should not result
// in multiple internal intersection observers being created for the iframe
// element, but instead should result in only one intersection observer
// associated with the iframe element, and the resulting navigation should
// be for the latest `src` attribute mutation.
const target = document.querySelector('#below_viewport');
target.src = 'resources/subframe.html?new-src';
target.scrollIntoView();
}));
const below_viewport_iframe_onload = t.step_func_done(() => {
const target = document.querySelector('#below_viewport');
// We check both of these to ensure that the `src` attribute and actual
// navigated resource do not get out-of-sync when navigating to lazy loaded
// resources.
assert_true(
target.src.includes('new-src'),
"The iframe's src should be updated to reflect the latest `src` " +
"mutation");
assert_true(
target.contentDocument.location.href.includes('new-src'),
'The iframe should be navigated to the resource provided by the latest ' +
'`src` mutation');
});
</script>
<body>
<div style="height:3000vh;"></div>
<iframe id="below_viewport" src="resources/subframe.html?old-src"
loading="lazy" width="200px" height="100px"
onload="below_viewport_iframe_onload();"></iframe>
</body>
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