javascript静态方法

<script type="text/javascript">
    //创建一个类Ju作为基类
    var Ju= function(name,dept){
        this.name = name || "none";
        this.dept = dept || "general";
    }

     Ju.prototype.toString = function(){  //toString是Employee类的常规方法
        return this.name + "&" + this.dept;
    }

     Ju.show = function (ep){      //show是Employee类的静态方法
        alert(ep.toString());
    }

    var exp = new Ju("fanrong","技术部");
     Ju.show(exp);          //只能由类调用,不能由实例对象调用.
    //exp.show(exp);            //这样回出错
</script>