function TimeSpan(h, m, s) {    this.h = Number(h);    this.m = Number(m);    this.s = Number(s);}TimeSpan.prototype = {    timer: null,    stop: function() {    },    callback: Function(),    start: function(callback) {        var self = this;        if (callback) {            this.callback = callback;        }        if (isNaN(this.s)) {            return;        }        self.timer = setInterval(function() {            self.s--;            if (self.s >= 0) {                self.callback();                return;            }            //s < 0, m > 0            if (self.m > 0) {                self.s = 59;                self.m--;                self.callback();                return;            }            //s < 0 ,m = 0, h<1            if (isNaN(self.h) || self.h < 1) {                //self.callback();                clearInterval(self.timer);                return;            }            self.m = 59;            self.s = 59;            self.h--            self.callback();        }, 1000);    }};

    var ts = new TimeSpan(hours, minutes, minutes);    ts.start(function(){        var s = this.s < 10 ? "0" + this.s : this.s;        var m = this.m < 10 ? "0" + this.m : this.m;         $(".clock .time").html(m + "分" + s + "秒");    });