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48 lines
1.8 KiB
HTML
48 lines
1.8 KiB
HTML
<!DOCTYPE html>
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<head>
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<title>Images with loading='lazy' load when in the viewport</title>
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<link rel="author" title="Chris Harrelson" href="mailto:chrishtr@chromium.org">
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<link rel="help" href="https://github.com/scott-little/lazyload">
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<script src="/resources/testharness.js"></script>
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<script src="/resources/testharnessreport.js"></script>
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</head>
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<!--
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Marked as tentative until https://github.com/whatwg/html/pull/3752 is landed.
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-->
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<script>
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const t = async_test("Test that images with loading='lazy' under multicol load once they enter the viewport.");
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let has_in_viewport_loaded = false;
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let has_window_loaded = false;
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const in_viewport_img_onload = t.step_func(function() {
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assert_false(has_in_viewport_loaded, "The in_viewport element should load only once.");
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has_in_viewport_loaded = true;
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});
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window.addEventListener("load", t.step_func_done(function() {
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assert_true(has_in_viewport_loaded, "The in_viewport element should have loaded before window.load().");
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assert_false(has_window_loaded, "The window.load() event should only fire once.");
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has_window_loaded = true;
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}));
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</script>
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<div class=texty style="column-count: 2; height: 300px">
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<div style="border: 1px solid black">
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<h2 style="column-span: all"></h2>
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<img loading="lazy" src="resources/image.png?first" width="160" height="120"
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onload="in_viewport_img_onload()">
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</div>
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</div>
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<!--
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This async script loads very slowly in order to ensure that, if the
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below_viewport element has started loading, it has a chance to finish
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loading before window.load() happens, so that the test will dependably fail
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in that case instead of potentially passing depending on how long different
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resource fetches take.
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-->
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<script async src="/common/slow.py"></script>
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