function openWindow()
    {
        var open=confirm("确定打开窗口吗？") ;
        if(open==true)
            {
                var url=prompt("确认打开的网址","http://www.imooc.com");
                if (url!=null)
                    {
                        window.open(url,"_blank","width=400px,height=500px,menubar=no,toolbar=no")
                    }
                else
                {
                    alert("已取消")
                }
            }
        else
            {
                alert("已取消");
            }
   
    }