function openWindow(){    var OpenNewwindow=confirm("打开imooc网站吗？");    var Newwindowurl;    if(OpenNewwindow==true)    {Newwindowurl="http://www.imooc.com/"}    else    {Newwindowurl="null"}    window.open(Newwindowurl,'_blank','width=400,height=500,menubar=no,toolbar=no');   }