<!doctype html>
<html>
<title>Lazyload images cannot load immediately from the list of available images if their tuple doesn't match other images in that list</title>
<link rel="author" title="Dom Farolino" href="mailto:[email protected]">
<link rel="author" title="Przemyslaw Gorszkowski" href="mailto:[email protected]">
<link rel="help" href="https://html.spec.whatwg.org/multipage/images.html#updating-the-image-data">
<link rel="help" href="https://html.spec.whatwg.org/multipage/urls-and-fetching.html#cors-settings-attribute">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<!-- A `loading=lazy` image will be placed below this div so that it is below
the viewport -->
<div id="img-container"></div>
<div style="height: 1000vh;"></div>
<div id="below-viewport-img-container"></div>
<script>
const image_path = 'resources/image.png?image-lazy-loading-lazy-different-crossorigin-' + Math.random();
promise_test(async t => {
await new Promise((resolve, reject) => {
const img = new Image();
img.onload = resolve;
img.onerror = e => { reject(new Error("The img should not fail to load")) };
document.querySelector('#img-container').append(img);
img.src = image_path;
});
// At this point, the image fetched eagerly above exists in the "list of
// available images". As per the spec's #updating-the-image-data algorithm [1]
// step 6, the "list of avalable images" is consulted before we take any
// lazyload-specific action. This means that lazyload images can load eagerly
// if they target a resource in the list of available images (includes cors
// settings attribute matching [2]). The image from "img-container" does not
// have "crossorigin" attribute and the lazyload image has crossorigin="anonymous".
// This means that lazyload image cannot be loaded eagerly from the list of available images.
// [1]: https://html.spec.whatwg.org/multipage/images.html#updating-the-image-data
// [2]: https://html.spec.whatwg.org/multipage/urls-and-fetching.html#cors-settings-attribute
const lazyload_image_promise = new Promise((resolve, reject) => {
const img = new Image();
img.loading = 'lazy';
img.crossOrigin = "anonymous";
img.onload = e => {
reject("The img should not be loaded from the list of available images because of different 'crossorigin'") };
img.onerror = e => { reject("The img should not fail to load") };
document.querySelector('#below-viewport-img-container').append(img);
img.src = image_path;
});
const timeout_promise = new Promise((resolve, reject) => {
t.step_timeout(() => {
resolve("The `loading=lazy` image should not load immediately from " +
"the list of available images because of different 'crossorigin'");
}, 2000);
});
// The `timeout_promise` should resolve first because lazyload image is not
// able to eagerly use resource from the "list of available images" if there
// is a difference in 'crossorigin'.
await Promise.race([lazyload_image_promise, timeout_promise]);
}, "Lazyload images cannot load immediately from the list of available images if their tuple doesn't match other images in that list");
</script>
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