JS面向对象的私有成员-变量实现方式

各位如果觉得有什么不妥的地方欢迎指出。

代码
(function JSClock(){
//partial class JSClock {                 
    var _timeID = null;

var _timeRunning = false;
    var _info;
    var _this;
    //构造函数
    function JSClock(elementId) {
        _this = this;
       _info =  document.getElementById(elementId);
    }
    JSClock.PRototype.getDateTime = function(){};//因为具体显示需求不同所以没实现
    JSClock.prototype.run = function() {
       var now = {};
       var tick = new Date();
       now.hours = tick.getHours();
       now.minutes = tick.getMinutes();
       now.seconds = tick.getSeconds();
       now.day = tick.getDay();
       now.month = tick.getMonth()+1;
       now.date = tick.getDate();
       now.year = tick.getYear();
       if (now.year < 1000) now.year += 1900;
       _timeRunning = true;
       _info.innerHTML = _this.getDateTime(now);
       _timeID = setTimeout(arguments.callee,1000);
    };
   
    JSClock.prototype.stop = function(){
        if(!_timeRunning)return
        clearTimeout(_timeID);
        _timeRunning = false;
    };
//}
    window.JSClock = JSClock;
})();