JS简单的倒计时(代码优化)

/*
* js简单的倒计时
* @param {date,obj} 日期 对象格式
*/ function CountDown(date,obj) {
var self = this;
self.date = date;
self.obj = obj;
self._init();
}; $.extend(CountDown.prototype,{ _init: function(){
var self = this,
obj = self.obj;
var dateTime = self._calculateTime(); if(obj.sec) {
$(obj.sec).html(dateTime.sec);
}
if(obj.mini) {
$(obj.mini).html(dateTime.mini);
}
if(obj.hour) {
$(obj.hour).html(dateTime.hour);
}
if(obj.day) {
$(obj.day).html(dateTime.day);
}
if(obj.month) {
$(obj.month).html(dateTime.month);
}
if(obj.year) {
$(obj.year).html(dateTime.year);
}
// setInterval 会有误差 大概每小时有5秒的误差 故用setTimeout做计时器 精准更高
t && clearTimeout(t);
var t = setTimeout(function(){
self._init();
}, 1000);
},
_zero: function(n){
var n = parseInt(n,10);
if(n > 0) {
if(n < 10) {
n = "0" + n;
}
return String(n);
}else {
return n = "00";
}
},
_calculateTime: function(){
var self = this,
date = self.date || Date.UTC(2050, 0, 1);
var end = new Date(date),
now = new Date(); // getTimezoneOffset() 方法可返回格林威治时间和本地时间之间的时差，以分钟为单位。
var leftTime = Math.round((end.getTime() - now.getTime())/1000) + end.getTimezoneOffset() * 60;
var obj = {
sec: "00",
mini: "00",
hour: "00",
day: "00",
month: "00",
year: "0"
};
if(leftTime > 0) {
obj.sec = self._zero(leftTime % 60);
obj.mini = Math.floor(leftTime / 60) > 0 ? self._zero(Math.floor(leftTime / 60) % 60) : "00";
obj.hour = Math.floor(leftTime / 3600) > 0 ? self._zero(Math.floor(leftTime/3600) % 24) : "00";
obj.day = Math.floor(leftTime / (24 * 3600)) > 0 ? self._zero(Math.floor(leftTime / (24*3600)) % 30) : "00";
obj.month = Math.floor(leftTime / (30 * 24 * 3600)) > 0 ? self._zero(Math.floor(leftTime / (30 * 24 * 3600)) % 12) : "00";
//年份，按按回归年360天秒算
obj.year = Math.floor(leftTime / (360 * 30 * 24 * 3600)) > 0 ? Math.floor(leftTime / (360 * 30 * 24 * 3600)) : "0";
}
return obj;
}
});

<span class="hour"></span>时 <span class="mini"></span>分 <span class="sec"></span>秒

var d = 1419509471000;
//var d = Date.UTC(2030, 6, 27, 16, 34);
var obj = {
sec: $(".sec"),
mini: $(".mini"),
hour: $(".hour")
}
new CountDown(d, obj);