modulepreload-referrer-check.html

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This WPT test may be referenced by the following Test IDs:
- /html/semantics/scripting-1/the-script-element/module/modulepreload-referrer-check.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<html>

<head>

<title>Modulepreload Referrer Header Check</title>

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

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

<script>

// Initialize the window.referrers object that will be used by echo-referrer.py

window.referrers = {};

</script>

</head>

<body>

<iframe id="test-frame"></iframe>

<script>

// This test uses a simple approach to check if modulepreload sends a referrer header

promise_test(async t => {

  const importId = Date.now();

  const preloadId = Date.now() + 1;

  // Import will set window.referrers[importId] to the referrer value

  await import(`/preload/resources/echo-referrer.py?uid=${importId}`);

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

  link.rel = 'modulepreload';

  link.href = `/preload/resources/echo-referrer.py?uid=${preloadId}`;

  // Wait for the preload to complete using onload event

  const preloadComplete = new Promise(resolve => {

    link.onload = resolve;

    link.onerror = () => {

      assert_unreached("Modulepreload failed to load");

};

});

  document.head.appendChild(link);

  await preloadComplete;

  // Second import ensures the module is loaded and referrer is recorded

  await import(`/preload/resources/echo-referrer.py?uid=${preloadId}`);

  // Check if referrers were recorded in the global window.referrers object

  assert_equals(window.referrers[importId], location.href, "Dynamic import should have a referrer header");

  assert_equals(window.referrers[preloadId], location.href, "Modulepreload should have a referrer header");

}, "Modulepreload should send a referrer header");

</script>

</body>

</html>