JavaScriptはカウントダウン効果を実現します.

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var CID = "endtime";//  
if(window.CID != null)
{
    var iTime = document.getElementById(CID).innerText;//  span    
    var Account;
    RemainTime();//  
}
function RemainTime()//     
{
    var iDay,iHour,iMinute,iSecond;
    var sDay="",sHour="",sMinute="",sSecond="",sTime="";
    if (iTime >= 0)
    {
        iDay = parseInt(iTime/24/3600);
        if (iDay > 0)
        {
            sDay = iDay + " ";
        }
        iHour = parseInt((iTime/3600)%24);
        if (iHour > 0){
            sHour = iHour + "  ";
        }
        iMinute = parseInt((iTime/60)%60);
        if (iMinute > 0){
            sMinute = iMinute + "  ";
        }
        iSecond = parseInt(iTime%60);
        if (iSecond >= 0){
            sSecond = iSecond + " ";
        }
        if ((sDay=="")&&(sHour=="")){
            sTime="<span style='color:darkorange'>" + sMinute+sSecond + "</font>";
        }
        else
        {
            sTime=sDay+sHour+sMinute+sSecond;
        }
        if(iTime==0){//   
            clearTimeout(Account);
              sTime="<span style='color:green'>    ！</span>";
        }
        else//         
        {
            Account = setTimeout("RemainTime()",1000);
        }
        iTime=iTime-1;
    }
    else
    {
            sTime="<span style='color:red'>     ！</span>";
    }
    document.getElementById(CID).innerHTML = sTime;//        span 
}