JS面向对象开发之私有成员变量实现方式

本文介绍的方法可能与网上流传的一些方法不太一样，这里是使用闭包来实现的。并以一个简单的时钟示例作为演示。

(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;
})();

//partial class JSClock{
    //virtual
    JSClock.prototype.getDateTime = function(now){
       var current,weekday;
       current = now.year + "年" + now.month + "月" + now.date + "日 " + ((now.hours >12) ? now.hours -12 :now.hours);
       current += ((now.minutes < 10) ? ":0" : ":") + now.minutes;
       current += ((now.seconds < 10) ? ":0" : ":") + now.seconds;
       current += (now.hours >= 12) ? " (下午)" : " (上午)";
       if(now.day==0) weekday = " 星期日";
       if(now.day==1) weekday = " 星期一";
       if(now.day==2) weekday = " 星期二";
       if(now.day==3) weekday = " 星期三";
       if(now.day==4) weekday = " 星期四";
       if(now.day==5) weekday = " 星期五";
       if(now.day==6) weekday = " 星期六";
       current += weekday;
       return current;
    };
//}

//测试
var time = new JSClock("test");
time.run();
//运行结果会在ID为test的元素中实时显示当前时间格式如：

//2010年2月6日 0:13:53 (上午) 星期六