stale-script.html - mozsearch

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This WPT test may be referenced by the following Test IDs:
- /fetch/stale-while-revalidate/stale-script.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<meta charset="utf-8">

<title>Tests Stale While Revalidate works for scripts</title>

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

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

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

<body>

<script>

const request_token = token();

const script_src = "./resources/stale-script.py?token=" + request_token;

// The script above will call report() via a uniquely generated ID on the

// subresource. If it is a cache hit, the ID will be the same and

// |last_modified_count| won't be incremented.

let last_modified;

let last_modified_count = 0;

function report(mod) {

  if (last_modified == mod)

    return;

  last_modified = mod;

  last_modified_count++;

let loadScript = async () => {

  let script = document.createElement("script");

  let script_loaded = new Promise(r => script.onload = r);

  script.src = script_src;

  document.body.appendChild(script);

  await script_loaded;

};

promise_test(async t => {

  await new Promise(r => window.onload = r);

  await loadScript();

  assert_equals(last_modified_count, 1, '(initial version loaded)');

  await loadScript();

  assert_equals(last_modified_count, 1, '(stale version loaded)');

  // Query the server again and again. At some point it must have received the

  // revalidation request. We poll, because we don't know when the revalidation

  // will occur.

  while(true) {

    await new Promise(r => step_timeout(r, 25));

    let response = await fetch(script_src + "&query");

    let count = response.headers.get("Count");

    if (count == '2')

      break;

  await loadScript();

  assert_equals(last_modified_count, 2, '(revalidated version loaded)');

}, 'Cache returns stale resource');

</script>

</body>