js实现网站运行时间统计

<span id="sitetime"></span><script language=javascript>    function siteTime(){        window.setTimeout("siteTime()", 1000);        var seconds = 1000;        var minutes = seconds * 60;        var hours = minutes * 60;        var days = hours * 24;        var years = days * 365;        var today = new Date();        var todayYear = today.getFullYear();        var todayMonth = today.getMonth()+1;        var todayDate = today.getDate();        var todayHour = today.getHours();        var todayMinute = today.getMinutes();        var todaySecond = today.getSeconds();        /* Date.UTC() -- 返回date对象距世界标准时间(UTC)1970年1月1日午夜之间的毫秒数(时间戳)        year - 作为date对象的年份，为4位年份值        month - 0-11之间的整数，做为date对象的月份        day - 1-31之间的整数，做为date对象的天数        hours - 0(午夜24点)-23之间的整数，做为date对象的小时数        minutes - 0-59之间的整数，做为date对象的分钟数        seconds - 0-59之间的整数，做为date对象的秒数        microseconds - 0-999之间的整数，做为date对象的毫秒数 */        var t1 = Date.UTC(2016,12,01,00,00,00); //北京时间2016-12-1 00:00:00        var t2 = Date.UTC(todayYear,todayMonth,todayDate,todayHour,todayMinute,todaySecond);        var diff = t2-t1;        var diffYears = Math.floor(diff/years);        var diffDays = Math.floor((diff/days)-diffYears*365);        var diffHours = Math.floor((diff-(diffYears*365+diffDays)*days)/hours);        var diffMinutes = Math.floor((diff-(diffYears*365+diffDays)*days-diffHours*hours)/minutes);        var diffSeconds = Math.floor((diff-(diffYears*365+diffDays)*days-diffHours*hours-diffMinutes*minutes)/seconds);        document.getElementById("sitetime").innerHTML=" 已运行"+diffYears+" 年 "+diffDays+" 天 "+diffHours+" 小时 "+diffMinutes+" 分钟 "+diffSeconds+" 秒";    }    siteTime();</script>

访问：http://www.liuyanzhao.com页脚，看效果