picture-loading-lazy.html

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This WPT test may be referenced by the following Test IDs:
- /html/semantics/embedded-content/the-img-element/picture-loading-lazy.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<head>

  <title>Images with loading='lazy' in picture elements load when near the viewport</title>

  <link rel="author" title="Raj T" href="mailto:rajendrant@chromium.org">

  <link rel="help" href="https://github.com/scott-little/lazyload">

  <script src="/resources/testharness.js"></script>

  <script src="/resources/testharnessreport.js"></script>

  <script src="../resources/common.js"></script>

</head>

<script>

const in_viewport_img = new ElementLoadPromise("in_viewport_img");

const lazy_attribute_img = new ElementLoadPromise("lazy_attribute_img");

const eager_attribute_img = new ElementLoadPromise("eager_attribute_img");

const document_load_promise = new Promise(resolve => {

  window.addEventListener("load", resolve);

});

async_test(function(t) {

  document_load_promise.then(t.step_func_done(function() {

    assert_false(lazy_attribute_img.element().complete);

    lazy_attribute_img.element().scrollIntoView();

  }));

}, "Test that the loading=lazy <picture> element below viewport was deferred, on document load.");

async_test(function(t) {

  in_viewport_img.promise.then(t.step_func_done());

}, "Test that in viewport <picture> element was loaded");

async_test(function(t) {

  eager_attribute_img.promise.then(t.step_func_done());

}, "Test that eager <picture> element was loaded");

async_test(function(t) {

  lazy_attribute_img.promise.then(t.step_func_done());

}, "Test that deferred <picture> element was loaded-in as well, after scrolled down");

</script>

<body>

<picture>

  <source sizes='50vw' srcset='resources/image.png?in_viewport_img'>

  <img id='in_viewport_img' src='img-not-loaded.png' loading="lazy" onload="in_viewport_img.resolve();">

</picture>

<div style="height:10000px;"></div>

<picture>

  <source sizes='50vw' srcset='resources/image.png?lazy_attribute_img'>

  <img id='lazy_attribute_img' src='img-not-loaded.png' loading="lazy" onload="lazy_attribute_img.resolve();">

</picture>

<picture>

  <source sizes='50vw' srcset='resources/image.png?eager_attribute_img'>

  <img id='eager_attribute_img' src='img-not-loaded.png' loading="eager" onload="eager_attribute_img.resolve();">

</picture>

<!--

  This async script loads very slowly in order to ensure that, if the

  below_viewport image 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>

</body>