js 实现 Privileged 方法

<script type="text/javascript">
function Container(param) {
    function dec() {
        if (secret > 0) {
            secret -= 1;
            return true;
        } else {
            return false;
        }
    }
    this.member = param;
    var secret = 3;
    var that = this;
    this.service = function () {
        return dec() ? that.member : null;
    };
}
myContainer = new  Container("terry...");
console.log(myContainer.service());
console.log(myContainer.service());
console.log(myContainer.service());
console.log(myContainer.service());
console.log(myContainer.member);
</script>