http://www.switchonthecode.com/tutorials/javascript-tutorial-simple-fade-animation


var TimeToFade = 1000.0;

function fade(eid)
{
  var element = document.getElementById(eid);
  if(element == null)
    return;
   
  if(element.FadeState == null)
  {
    if(element.style.opacity == null
        || element.style.opacity == ''
        || element.style.opacity == '1')
    {
      element.FadeState = 2;
    }
    else
    {
      element.FadeState = -2;
    }
  }

  if(element.FadeState == 1 || element.FadeState == -1)
  {
    element.FadeState = element.FadeState == 1 ? -1 : 1;
    element.FadeTimeLeft = TimeToFade - element.FadeTimeLeft;
  }
  else
  {
    element.FadeState = element.FadeState == 2 ? -1 : 1;
    element.FadeTimeLeft = TimeToFade;
    setTimeout("animateFade(" + new Date().getTime() + ",'" + eid + "')", 33);
  }  
    	
}

function animateFade(lastTick, eid)
{  
  var curTick = new Date().getTime();
  var elapsedTicks = curTick - lastTick;
 
  var element = document.getElementById(eid);
 
  if(element.FadeTimeLeft <= elapsedTicks)
  {
    element.style.opacity = element.FadeState == 1 ? '1' : '0';
    element.style.filter = 'alpha(opacity = '
        + (element.FadeState == 1 ? '100' : '0') + ')';
    element.FadeState = element.FadeState == 1 ? 2 : -2;
    return;
  }
 
  element.FadeTimeLeft -= elapsedTicks;
  var newOpVal = element.FadeTimeLeft/TimeToFade;
  if(element.FadeState == 1)
    newOpVal = 1 - newOpVal;

  element.style.opacity = newOpVal;
  element.style.filter = 'alpha(opacity = ' + (newOpVal*100) + ')';
 
  setTimeout("animateFade(" + curTick + ",'" + eid + "')", 33);
}

function swapBackground(theurl)
{
	var element = document.getElementById('fadeback');
	
	element.style.backgroundImage="url("+theurl+")";
}
function swapImage(theurl)
{
	var element = document.getElementById('fadefront');
	
	element.src=theurl;
		
}
var action_is_on=0;

function action()
{
	setTimeout("fade('fadefront')", 7000);
	setTimeout("swapImage('templates/default-3cols/images/maincontentbackground3.jpg')", 10000);
	
	setTimeout("fade('fadefront')", 13000);
	setTimeout("swapBackground('templates/default-3cols/images/maincontentbackground4.jpg')", 16000);
	
	setTimeout("fade('fadefront')", 19000);
	setTimeout("swapImage('templates/default-3cols/images/maincontentbackground1.jpg')", 22000);
	
	setTimeout("fade('fadefront')",25000);
	setTimeout("swapBackground('templates/default-3cols/images/maincontentbackground2.jpg')", 27000);
	
	
	setTimeout("action()", 27000);
}

function doAction(){
	if (!action_is_on)
	{
		action_is_on=1;
		action();
	}
}