js实现网页倒计时、网站已运行时间功能的代码2例

1.显示格式：距离结束时间还有：00天05小时25分30秒（秒为跑秒）

代码如下：

<div id="time" class="time"></div>
<script language=javascript>    
function show\_date\_time(){   
 window.setTimeout("show\_date\_time()", 1000);   
 target=new Date(2017,02,08,0,0,0);  //注意：表示月份的参数介于 0 到 11 之间。也就是说，如果希望把月设置为8月，则参数应该是7。
 today=new Date(); 

 timeold=(target.getTime()-today.getTime());   

 sectimeold=timeold/1000   
 secondsold=Math.floor(sectimeold);   
 msPerDay=24\*60\*60\*1000   
 e\_daysold=timeold/msPerDay   
 daysold=Math.floor(e\_daysold);   
 e\_hrsold=(e\_daysold-daysold)\*24;   
 hrsold=Math.floor(e\_hrsold);   
 e\_minsold=(e\_hrsold-hrsold)\*60;   
 minsold=Math.floor((e\_hrsold-hrsold)\*60);   
 seconds=Math.floor((e\_minsold-minsold)\*60);   

  if (daysold<0) {   
  document.getElementById("time").innerHTML="逾期,倒计时已经失效";   
}   
 else{   
 if (daysold<10) {daysold="0"+daysold}   
 if (hrsold<10) {hrsold="0"+hrsold}   
 if (minsold<10) {minsold="0"+minsold}   
 if (seconds<10) {seconds="0"+seconds}   
 if (daysold>0) {   
  document.getElementById("time").innerHTML="距离结束时间还有："+daysold+"天"+hrsold+"小时"+minsold+"分"+seconds+"秒";   
 }   
 else   
  document.getElementById("time").innerHTML="<font color=red>距离结束时间还有："+daysold+"天"+hrsold+"小时"+minsold+"分"+seconds+"秒</font>";  //结束时间小于1天，字体呈红色提醒
}   
}   
show\_date\_time();   
</script>

2.显示格式：已运行0 年 1 天 0 小时 4 分钟 35 秒（秒为跑秒）

代码如下：

<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(2014,0,14,11,19,00)
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>

注意：如果需要一共还有多少天数用%D,参数说明：

Y: "years"
m: "months"
w: "weeks"
d: "days"
D: "totalDays"
H: "hours"
M: "minutes"
S: "seconds"