function NavDate() {
var self = this;
var Day = new Array("星期日", 
       "星期一", 
       "星期二",
       "星期三",
       "星期四",
       "星期五",
       "星期六");
var engDay = new Array("Sun","Mon","Wed","Thurs","Fri","Sat");

this.elementId = undefined;
this.formatString = "YYYY年MM月DD日 WWW hh:mm:ss";
this.runtime = false;
this.interval = undefined;
this.daydesc = "cn";
this.hourdesc = 24;


this.Run = function() {
   if(self.elementId==undefined) return;
   if(self.runtime) {
    self.printDate();
    self.interval = window.setInterval(self.printDate,1000);
   }else{
    self.printDate();
   }
}

this.printDate = function() {
   var Now = new Date();
   var Year = Now.getFullYear();
   var Month = Now.getMonth() + 1;
   Month = Month>9 ? Month : ("0"+Month);
   var date = Now.getDate();
   date = date>9 ? date : ("0"+date);
   var day = Now.getDay();
   var Hour = Now.getHours();
   if(self.hourdesc==12) Hour-=12;
   Hour = Hour>9 ? Hour : ("0"+Hour);
   var Minute = Now.getMinutes();
   Minute = Minute>9 ? Minute : ("0"+Minute);
   var Second = Now.getSeconds();
   Second = Second>9 ? Second : ("0"+Second);
  
   var format = self.formatString;
   format = format.replace("YYYY",Year);
   format = format.replace("MM",Month);
   format = format.replace("DD",date);
   if(self.daydesc=="cn") {
    format = format.replace("WK",Day[day]);
   }else if(self.daydesc=="us") {
    format = format.replace("WK",engDay[day]);
   }
   format = format.replace("hh",Hour);
   format = format.replace("mm",Minute);
   format = format.replace("ss",Second);
  
   document.getElementById(self.elementId).innerHTML = format;
}
}