non sapendo come modificare il mio post recente, questa è la funzione che richiama il countdown
codice HTML:
function startGrbTimer(duration, display) {    
var timer = duration, hours, minutes, seconds;    
setInterval(function () {        
days = parseInt(timer / 3600 / 24, 10);
        hours = parseInt(timer % 3600 / 60 / 24, 10); 
       minutes = parseInt(timer % 3600 / 60, 10);   
     seconds = parseInt(timer % 60, 10);
        hours = hours < 10 ? "0" + hours : hours;    
    minutes = minutes < 10 ? "0" + minutes : minutes;  
      seconds = seconds < 10 ? "0" + seconds : seconds;
        display.textContent = days + " day" + (days > 1 ? "s" : "") + ", " + hours + " hours, " +  minutes + " minutes, " + seconds + " seconds";
        if (--timer < 0) {           
 timer = duration;       
 }
    }, 1000);
}