JS覆寫父類私人欄位方法成功

<script language="javascript">

    function p() {
        var self = this;
        var m = "p";

        var getName = function () { return m; }

        self.alert = function () {
            var res = eval("(" + getName.toString() + ")()");
            alert(res);
        }

        self.OverWrite_getName = function (action) {
            getName = action;
        }
    }

    function c() {
        var self = this;

        var getName = function () {
            return m + m;
        }

        self.New_getName = function () {
            return getName;
        }
    }
    var base = new p();
    c.prototype = base;

    var c1 = new c();
    base.OverWrite_getName(c1.New_getName());
    c1.alert();

</script>