html-preload-image.html

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This test has a WPT meta file that expects 1 subtest issues.
This WPT test may be referenced by the following Test IDs:
- /jpegxl/html-preload-image.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<title>JPEG XL integration: link rel=preload as=image</title>

<link rel="help" href="https://github.com/web-platform-tests/interop-jpegxl">

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

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

<script>

promise_test(async () => {

  const href = new URL('resources/3x3_srgb_lossless.jxl', location.href).toString();

  const preload = document.createElement('link');

  preload.rel = 'preload';

  preload.as = 'image';

  preload.href = href;

  const preloadDone = new Promise((resolve, reject) => {

    preload.onload = resolve;

    preload.onerror = () => reject(new Error('preload failed'));

});

  document.head.appendChild(preload);

  await preloadDone;

  const img = new Image();

  const loaded = new Promise((resolve, reject) => {

    img.onload = resolve;

    img.onerror = () => reject(new Error('image failed after preload'));

});

  img.src = href;

  await loaded;

  assert_greater_than(img.naturalWidth, 0);

  assert_true(performance.getEntriesByName(href).length > 0,

      'resource timing should include the JPEG XL image request');

}, '<link rel=preload as=image> preloads JPEG XL image');

</script>