倒计时模块（获取的是服务器上的时间——适合购物网站的抢购模块）

JS部分

/*ajax请求服务器当前时间*/
function servertiems() {   
  var A=null;
  try {
    A=new ActiveXObject("Msxml2.XMLHTTP") 
  } catch(e) {
    try {
      A=new ActiveXObject("Microsoft.XMLHTTP") 
    } catch(oc) {
      A=null
    }
  }
  if ( !A && typeof XMLHttpRequest != "undefined" ) { 
    A=new XMLHttpRequest()
  }
  return A
}
  var NowTime;
  var tm = servertiems();  
  var strData="auto="+new Date().toString(); 
  tm.onreadystatechange = callback_st;
  tm.open("GET","http://您的服务器输出地址",false);//服务器输出格式如：{"time": "2016/4/29 11:24:11"}
  tm.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
  tm.send(strData); 
  
function callback_st(){
    if (tm.readyState==4 && tm.status==200){
    var result = tm.responseText;    
    var json = eval("(" + result + ")");
    NowTime=json.time;//获取到服务器当前时间
    
    }
}



var today=new Date(NowTime).getTime();
var now = new Date().getTime();
var diff = (now - today);

function show_date_timezj(timesxx,xid){ 
window.setTimeout(function(){show_date_timezj(timesxx,xid)},20); 
BirthDay=new Date(timesxx);//设置日期
var now_fun = new Date().getTime();
var todayx=now_fun - diff;
timeold=(BirthDay - now_fun + diff );
sectimeold=timeold/1000;
secondsold=Math.floor(sectimeold); 
msPerDay=86400000; 

//*天数
e_daysold=timeold/msPerDay;
daysold=Math.floor(e_daysold); 

//*小时
e_hrsold=(e_daysold-daysold)*24; 
hrsold=Math.floor(e_hrsold); 
e_minsold=(e_hrsold-hrsold)*60;
minsold=Math.floor((e_hrsold-hrsold)*60); 
e_seconds = (e_minsold-minsold)*60;
seconds=Math.floor((e_minsold-minsold)*60); 
ms = e_seconds-seconds;
ms = new String(ms)
ms = ms.substr(2,3);

if(daysold>=0){
document.getElementById(xid).innerHTML="<span>距离开始时间还有: <font color='#ff0000'>"+(daysold<10?'0'+daysold:daysold)+"</font>天</span>"+"<span><font color='#ff0000'>"+(hrsold<10?'0'+hrsold:hrsold)+"</font>小时</span>"+"<span><font color='#ff0000'>"+(minsold<10?'0'+minsold:minsold)+"</font>分</span>"+"<span><font color='#ff0000'>"+(seconds<10?'0'+seconds:seconds)+"</font>秒</span>"+"<span><font color='#ff0000'>"+ms+"</font><span>";
}else{
document.getElementById(xid).innerHTML='';
document.getElementById(xid).nextSibling.className='';
}

}

HTML部分

<div>
<div id="span_k1"></div><a href="" class="no_ac">进入</a>
<div id="span_k2"></div><a href="" class="no_ac">进入</a>
<div id="span_k3"></div><a href="" class="no_ac">进入</a>
</div>

 JS调用

var spank1=new show_date_timezj("05/06 /2015 19:30:00","span_k1");
var spank2=new show_date_timezj("05/07 /2015 09:00:00","span_k2");
var spank3=new show_date_timezj("05/08 /2015 19:00:00","span_k3");