// In an earlier version of the HTML Standard, document open steps had "prompt // to unload document" as a step. Test that this no longer happens. async_test(t => { const frame = document.body.appendChild(document.createElement("iframe")); t.add_cleanup(() => frame.remove()); frame.src = "/common/blank.html"; frame.onload = t.step_func(() => { frame.contentWindow.onbeforeunload = t.unreached_func("beforeunload should not be fired"); frame.contentDocument.open(); t.step_timeout(t.step_func_done(() => { // If the beforeunload event has still not fired by this point, we // consider the test a success. `frame.remove()` above will allow the // `load` event to be fired on the top-level Window, thus unblocking // testharness. }), 500); }); }, "document.open() should not fire a beforeunload event");