chromium/third_party/blink/web_tests/external/wpt/preload/supported-as-values.html

<!DOCTYPE html>
<html>
<title>Test the supported value for &lt;link rel=preload as="..."&gt;</title>
<meta name="timeout" content="long">
<meta name="variant" content="?as=image&expected=1">
<meta name="variant" content="?as=fetch&expected=1">
<meta name="variant" content="?as=font&expected=1">
<meta name="variant" content="?as=script&expected=1">
<meta name="variant" content="?as=style&expected=1">
<meta name="variant" content="?as=track&expected=1">

<meta name="variant" content="?as=garbagefoobar&expected=0">
<meta name="variant" content="?as=video&expected=0">
<meta name="variant" content="?as=audio&expected=0">
<meta name="variant" content="?as=object&expected=0">
<meta name="variant" content="?as=iframe&expected=0">
<meta name="variant" content="?as=worklet&expected=0">
<meta name="variant" content="?as=json&expected=0">

<script src="/common/utils.js"></script>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<body>
<script>
    const params = new URLSearchParams(location.search);
    const as = params.get("as");
    const expected = Number(params.get("expected"));
    promise_test(async t => {
        const link = document.createElement("link");
        link.href = new URL("/common/echo.py?content=nothing", location.href).href;
        link.rel = "preload";
        link.as = as;
        document.head.append(link);
        await new Promise(resolve => {
            t.step_timeout(resolve, 1000);
            link.addEventListener("load", resolve);
            link.addEventListener("error", resolve);
        });
        const resources = performance.getEntriesByName(link.href);
        assert_equals(resources.length, expected);
    });
</script>
</body>
</html>