<script type="text/javascript"> 
  function openWindow(){
    var con = confirm("是否打开网页？");
    if(con=="true"){
        var win = prompt("请输入要打开的网址","http://www/imooc.com");
        if(win!=null){
         window.open(win,'_blank','width=400,height=500,menubar=no,toolbar=no');
        }else{
            alert('出错啦！');
        }
    }else{
        alert('出错~');
    }  
  }
  </script>