stylesheet-media-change-no-fetch.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:
- /html/semantics/document-metadata/the-link-element/stylesheet-media-change-no-fetch.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<meta charset="utf-8">

<title>stylesheet should not re-fetch when media changes. The media change should apply immediately</title>

<link rel="help" href="https://html.spec.whatwg.org/multipage/links.html#link-type-stylesheet">

<link rel="help" href="https://html.spec.whatwg.org/multipage/semantics.html#processing-the-media-attribute">

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

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

<style>

p {

    color: red;

</style>

<body></body>

<script>

  promise_test(async t => {

    const link = document.createElement("link");

    function waitForStylesheet() {

      return new Promise(resolve => link.addEventListener("load", resolve, {once: true}));

    link.media = "none";

    link.rel = "stylesheet";

    link.href = "resources/good.css";

    const p = document.createElement("p");

    p.textContent = "hello";

    document.body.appendChild(p);

    document.body.appendChild(link);

    await waitForStylesheet();

    assert_equals(getComputedStyle(p).color, "rgb(255, 0, 0)");

    link.media = "all";

    assert_equals(getComputedStyle(p).color, "rgb(0, 128, 0)");

    const loaded = waitForStylesheet().then(() => "load");

    const timeout = new Promise(resolve => t.step_timeout(() => resolve("timeout"), 100));

    const result = await Promise.race([loaded, timeout]);

    assert_equals(result, "timeout");

});

</script>