fullscreen/api/element-request-fullscreen-top.html

<!DOCTYPE html>
<title>
    Element#requestFullscreen() for top element in fullscreen element stack
</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/testdriver.js"></script>
<script src="/resources/testdriver-vendor.js"></script>
<script src="../trusted-click.js"></script>
<div id="log"></div>
<div id="top"></div>
<script>
    promise_test(async function (t) {
        const top = document.getElementById("top");
        document.onfullscreenerror = t.unreached_func("fullscreenerror event");

        await Promise.all([
            trusted_request(top),
            new Promise((r) =>
                document.addEventListener("fullscreenchange", r)
            ),
        ]);
        assert_equals(document.fullscreenElement, top);
        await trusted_click(top);
        await top.requestFullscreen();
        // A fullscreenerror event would be fired after an async section
        // and an animation frame task, so wait until after that.
        await new Promise((resolve) => {
            t.step_timeout(() => {
                requestAnimationFrame(resolve);
            });
        });
    });
</script>