js实现倒计时效果(年月日时分秒)

/* 
* 倒计时的实现
*/
var fnTimeCountDown = function (d, o, now, callback) {
    var f = {
        zero: function (n) {
            var n = parseInt(n, 10);
            if (n > 0) {
                if (n <= 9) {
                    n = "0" + n;
                }
                return String(n);
            } else {
                return "00";
            }
        },
        dv: function () {
            d = d || Date.UTC(2050, 0, 1); //如果未定义时间，则我们设定倒计时日期是2050年1月1日
            var future = new Date(d);
            var nowTime = new Date(now);
            //现在将来秒差值
            var dur = Math.round((future.getTime() - nowTime.getTime()) / 1000), pms = {
                sec: "00",
                mini: "00",
                hour: "00",
                day: "00",
                month: "00",
                year: "0"
            };
            if (dur > 0) {
                pms.sec = f.zero(dur % 60);
                pms.mini = Math.floor((dur / 60)) > 0 ? f.zero(Math.floor((dur / 60)) % 60) : "00";
                pms.hour = Math.floor((dur / 3600)) > 0 ? f.zero(Math.floor((dur / 3600)) % 24) : "00";
                //pms.day = Math.floor((dur / 86400)) > 0 ? f.zero(Math.floor((dur / 86400)) % 30) : "00";
                pms.day = Math.floor((dur / 86400)) > 0 ? f.zero(Math.floor(dur / 86400)) : "00";
                //月份，以实际平均每月秒数计算
                pms.month = Math.floor((dur / 2629744)) > 0 ? f.zero(Math.floor((dur / 2629744)) % 12) : "00";
                //年份，按回归年365天5时48分46秒算
                pms.year = Math.floor((dur / 31556926)) > 0 ? Math.floor((dur / 31556926)) : "0";
            }
            return pms;
        },
        ui: function () {
            if (o.sec) {
                o.sec.innerHTML = f.dv().sec;
            }
            if (o.mini) {
                o.mini.innerHTML = f.dv().mini;
            }
            if (o.hour) {
                o.hour.innerHTML = f.dv().hour;
            }
            if (o.day) {
                o.day.innerHTML = f.dv().day;
            }
            if (o.month) {
                o.month.innerHTML = f.dv().month;
            }
            if (o.year) {
                o.year.innerHTML = f.dv().year;
            }
            now = now + 1000;
            if (f.dv().sec == "00" && f.dv().mini == "00" && f.dv().hour == "00" && f.dv().day == "00" && f.dv().month == "00" && f.dv().year == "0") {
                if (callback) {
                    callback();
                }
            }
 
            setTimeout(f.ui, 1000);
        }
    };
    f.ui();
};