function openWindow(){
        var world = window.confirm('请输入网址：');
        if(world)
        {
           var home=window.prompt('请输入网址：','http://www.imooc.com/');
           if(home !== null)
           {
                window.open(home,'_black','width=400,height=500,menubar=no,toolbar=no');
           }
        }
        else
        {
            document.write("下次再来");
        }
    }