(function(){
    const ifr = document.createElement('iframe');
    const ifr2 = document.createElement('iframe');
    document.body.appendChild(ifr);
    const div = document.createElement('div');
    div.id='0';
    setTimeout(() => { ifr2.contentWindow.alert.call(top,1); }, 500);
    try { ifr.contentWindow.document.body.appendChild(div); } catch {}
    document.body.appendChild(ifr2);
}());