setInterval ( "uptime()",1000 ) ;
 var ut_second = -10;

 function createXmlHttp() {
   //ref:http://www.hawk.34sp.com/stdpls/xml/xmlhttprequest.html
   return this.XMLHttpRequest ? 
     new XMLHttpRequest() : new ActiveXObject("Microsoft.XMLHTTP");
 }

 function flash(n){
   var url="/uptime.20060802.php";
   var xmlhttp = createXmlHttp();
   xmlhttp.onreadystatechange =function(){
     if (xmlhttp.readyState == 4) {
       disptime(xmlhttp.responseText);
       //h.innerHTML=xmlhttp.responseText;
     }
   };
   
   xmlhttp.open("GET",url , true);
   xmlhttp.setRequestHeader("Content-Type" , "application/x-www-form-urlencoded");
   xmlhttp.setRequestHeader("If-Modified-Since","null");
     //ref:http://www.semblog.org/msano/archives/000386.html
   xmlhttp.send("");
   
 }

 function disptime(n){
   var d = document.getElementById("day");
   var h = document.getElementById("hour");
   var m = document.getElementById("mini");
   var s = document.getElementById("sec");
   var sec = n%60;
   s.innerHTML=sec;
   ut_second = sec;
   n = (n-sec)/60;
   var min = n%60;
   m.innerHTML=min;
   n = (n-min)/60;
   var hou = n%24;
   h.innerHTML=hou;
   n = (n-hou)/24;
   var day = n;
   d.innerHTML=day;
 }

 function uptime(){
   ut_second +=1;
   if(ut_second == -9 || ut_second == 60){  //更新頻度をあげたい場合はここを変更
     flash();
     //alert("sync");
   }else if(ut_second < 0 || ut_second >=60){ //安全策(?)同期に1秒以上かかったりした場合のため
     flash();
   }else{
     var s = document.getElementById("sec");
     s.innerHTML = ut_second;
   }
 }