web-nfc/NDEFReader-write-document-hidden-manual.https.html

<!DOCTYPE html>
<meta charset="utf-8">
<meta name="timeout" content="long">
<title>NDEFReader.write respect page visibility changes</title>
<link rel="help" href="https://w3c.github.io/web-nfc/#visible-document">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/nfc-helpers.js"></script>
<script>

promise_test(async t => {
  const writer = new NDEFReader();
  const p1 = writer.write(test_text_data);

  return await new Promise((resolve, reject) => {
    p1.then(() => {
      assert_false(document.hidden);
      resolve();
    }).catch(e => {
      reject();
    });
  });
}, "Test NDEFReader.write operation should be suspended when document is not visible");

</script>

<p>Step1: switch the page to the background, then tap an NFC tag.</p>
<p>Step2: switch back to the page, then tap the tag again.</p>