fullscreen/api/element-request-fullscreen-active-document.html

<!DOCTYPE html>
<title>Element#requestFullscreen() when the document is not the active document</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<div id="log"></div>
<iframe allowfullscreen></iframe>
<script>
var t = async_test();

onload = t.step_func(() => {
  var iframe = document.querySelector("iframe");
  var documentBeforeNav = iframe.contentDocument;
  documentBeforeNav.onfullscreenchange = t.unreached_func('fullscreenchange event');
  documentBeforeNav.onfullscreenerror = t.unreached_func('fullscreenerror event');

  iframe.onload = t.step_func(() => {
    var p = documentBeforeNav.documentElement.requestFullscreen();
    // If a promise was returned, it should already be rejected, so its reject
    // callback should be invoked before a second promise's callback.
    // This test does not fail if promises aren't implemented.
    if (p) {
      var rejected = false;
      p.catch(t.step_func(() => rejected = true));
      Promise.resolve().then(t.step_func(() => assert_true(rejected)));
    }
    // Per spec the fullscreenerror event should be fired at the next animtion
    // frame, but at least Gecko and WebKit will instead effectively do "queue a
    // task to fire ...". Use both rAF and setTimeout to fail even if the timing
    // of the (unexpected) event isn't as expected.
    requestAnimationFrame(t.step_func(() => {
      step_timeout(t.step_func_done());
    }));
  });

  // Navigate the iframe
  window[0].location.href = '/common/blank.html';
});
</script>