var BookAds = 4;
var BookAdN = 1;

var delays = [10, 10, 10, 20, 20];
// var delays = [1, 1, 1, 1, 10];

function NextBookAd() {
   self.status = BookAdN + ' (' + delays[BookAdN] + 's)';
   var i;
   for(i = 0; i <= BookAds; i++) {
      var el = document.getElementById('BookAd' + i);
      if(i == BookAdN) { el.className = 'BookAdOn'} else { el.className = 'BookAd' }
   }
   StartBookTimer(delays[BookAdN]);
   BookAdN = (BookAdN+1) % (BookAds+1);
}

var secs;
var timerID = null;
var timerRunning = false;

function InitializeAds(bookads, d)
{
   BookAds = bookads;
   delays = d;
//   alert('BookAds = ' + BookAds + '; delays = ' + delays[0] + ',' + delays[1]);
}

function InitializeTimer()
{
   StopBookTimer();
   NextBookAd();
}

function StopBookTimer()
{
   if(timerRunning)
     clearTimeout(timerID);
   timerRunning = false
}
    
function StartBookTimer(delay)
{
   timerRunning = true;
   timerID = self.setTimeout("NextBookAd()", delay*1000);
}