【JS】网站运行时间

<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()
            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(2017,2,11,00,00,00)
            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" */
            document.getElementById("sitetime").innerHTML=" 很努力地存活了 "+(diffYears*365+diffDays)+" 天 "+diffHours+" 小时 "+diffMinutes+" 分钟 "+diffSeconds+" 秒"
            }
            siteTime()
            </script>