fullscreen/api/element-ready-check-fullscreen-element-sibling-manual.html

<!DOCTYPE html>
<title>Element ready check for sibling of fullscreen element</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="../trusted-click.js"></script>
<div id="log"></div>
<div id="a"></div>
<div id="b"></div>
<script>
async_test(function(t)
{
    var a = document.getElementById("a");
    var b = document.getElementById("b");
    document.onfullscreenchange = t.step_func(function()
    {
        assert_equals(document.fullscreenElement, a, "fullscreen element");
        trusted_request(t, b, a);
        document.onfullscreenchange = t.unreached_func("second fullscreenchange event");
        document.onfullscreenerror = t.step_func_done();
    });
    trusted_request(t, a);
});
</script>