只弹得出一个确认提示框，什么问题

function openWindow(){
        var mycc = confirm("是否打开");
        if(mycc==true){
            var address=prompt("请输入网址","http://www.imooc.com/");
     window.open(address,'mukewang','_blank','width=400px,height=500px,menubar=no,toolbar=no');}
        else{
            alert("nothing");
        }
        }