Date.prototype.toString=function(format){
    var time={};
    time.Year=this.getFullYear();
    time.TYear=(""+time.Year).substr(2);
    time.Month=this.getMonth()+1;
    time.TMonth=time.Month<10?"0"+time.Month:time.Month;
    time.Day=this.getDate();
    time.TDay=time.Day<10?"0"+time.Day:time.Day;
    time.Hour=this.getHours();
    time.THour=time.Hour<10?"0"+time.Hour:time.Hour;
    time.hour=time.Hour<13?time.Hour:time.Hour-12;
    time.Thour=time.hour<10?"0"+time.hour:time.hour;
    time.Minute=this.getMinutes();
    time.TMinute=time.Minute<10?"0"+time.Minute:time.Minute;
    time.Second=this.getSeconds();
    time.TSecond=time.Second<10?"0"+time.Second:time.Second;
    time.Millisecond=this.getMilliseconds();

    var oNumber=time.Millisecond/1000;

    if(format!=undefined && format.replace(/\s/g,"").length>0){
    format=format
        .replace(/yyyy/ig,time.Year)
        .replace(/yyy/ig,time.Year)
        .replace(/yy/ig,time.TYear)
        .replace(/y/ig,time.TYear)
        .replace(/MM/g,time.TMonth)
        .replace(/M/g,time.Month)
        .replace(/dd/ig,time.TDay)
        .replace(/d/ig,time.Day)
        .replace(/HH/g,time.THour)
        .replace(/H/g,time.Hour)
        .replace(/hh/g,time.Thour)
        .replace(/h/g,time.hour)
        .replace(/mm/g,time.TMinute)
        .replace(/m/g,time.Minute)
        .replace(/ss/ig,time.TSecond)
        .replace(/s/ig,time.Second)
        .replace(/fff/ig,time.Millisecond)
        .replace(/ff/ig,oNumber.toFixed(2)*100)
        .replace(/f/ig,oNumber.toFixed(1)*10);
    }
    else{
        format=time.Year+"-"+time.Month+"-"+time.Day+" "+time.Hour+":"+time.Minute+":"+time.Second;
    }
    return format;
}

var d=new Date();
console.log(d.toString());    //2011-12-29 11:29:43
console.log(d.toString(""));    //2011-12-29 11:29:43
console.log(d.toString("yyyy-MM-dd"));    //2011-12-29
console.log(d.toString("HH:mm:ss"));    //11:29:43
console.log(d.toString("yyyy-MM-dd HH:mm:ss"));    //2011-12-29 11:29:43
console.log(d.toString("yyyy年MM月dd日 HH:mm:ss"));    //2011年12月29日 11:29:43
console.log(d.toString("yyyy-MM-dd HH:mm:ss fff"));    //2011-12-29 11:29:43 862