// JavaScript Document
var timer=window.setTimeout('cache()',1);
function cache() {
	for (var i = 1; i<=5; i++) {
		if(document.getElementById('smenu'+i))
		{
			document.getElementById('smenu'+i).style.visibility = "hidden";
		}
		if(document.getElementById('over'+i))
		{
			document.getElementById('over'+i).style.visibility = "visible";
		}
		if (document.getElementById('out'+i))
		{
			document.getElementById('out'+i).style.visibility = "hidden";
		}
	}
}
function cache_projet() {
	document.getElementById('over1').style.background='url(../img/commun/votreprojet_active.jpg)';
	document.getElementById('over1').style.backgroundRepeat='no-repeat';
	document.getElementById('over1').style. backgroundPosition='top left';
for (var i = 1; i<=5; i++) {
	document.getElementById('smenu'+i).style.visibility = "hidden";
	document.getElementById('over'+i).style.visibility = "visible";
		if (document.getElementById('out'+i)) {
			document.getElementById('out'+i).style.visibility = "hidden";
		}
	}
}
function cache_savoir() {
	document.getElementById('over2').style.background='url(../img/commun/savoir_active.jpg)';
	document.getElementById('over2').style.backgroundRepeat='no-repeat';
	document.getElementById('over2').style. backgroundPosition='top left';
for (var i = 1; i<=5; i++) {
	document.getElementById('smenu'+i).style.visibility = "hidden";
	document.getElementById('over'+i).style.visibility = "visible";
		if (document.getElementById('out'+i)) {
			document.getElementById('out'+i).style.visibility = "hidden";
		}
	}
}
function cache_offres() {
	document.getElementById('over3').style.background='url(../img/commun/offres_active.jpg)';
	document.getElementById('over3').style.backgroundRepeat='no-repeat';
	document.getElementById('over3').style. backgroundPosition='top left';
for (var i = 1; i<=5; i++) {
	document.getElementById('smenu'+i).style.visibility = "hidden";
	document.getElementById('over'+i).style.visibility = "visible";
		if (document.getElementById('out'+i)) {
			document.getElementById('out'+i).style.visibility = "hidden";
		}
	}
}
function cache_valeurs() {
	document.getElementById('over4').style.background='url(../img/commun/val_active.jpg)';
	document.getElementById('over4').style.backgroundRepeat='no-repeat';
	document.getElementById('over4').style. backgroundPosition='top left';
for (var i = 1; i<=5; i++) {
	document.getElementById('smenu'+i).style.visibility = "hidden";
	document.getElementById('over'+i).style.visibility = "visible";
		if (document.getElementById('out'+i)) {
			document.getElementById('out'+i).style.visibility = "hidden";
		}
	}
}
function cache_groupe() {
	document.getElementById('over5').style.background='url(../img/commun/groupe_active.jpg)';
	document.getElementById('over5').style.backgroundRepeat='no-repeat';
	document.getElementById('over5').style. backgroundPosition='top left';
for (var i = 1; i<=5; i++) {
	document.getElementById('smenu'+i).style.visibility = "hidden";
	document.getElementById('over'+i).style.visibility = "visible";
		if (document.getElementById('out'+i)) {
			document.getElementById('out'+i).style.visibility = "hidden";
		}
	}
}
function time (){
timer=window.setTimeout('cache()',50);
}
function montre(id,id2) {
clearTimeout(timer);
var d = document.getElementById(id);
var e = document.getElementById(id2);
	for (var i = 1; i<=5; i++) {
		if (document.getElementById('smenu'+i)) {
			document.getElementById('smenu'+i).style.visibility = "hidden";
		}
	}

if (id){
d.style.visibility = "visible";
}
if (id2){
e.style.visibility = "visible";
}
}

Example: preloadImages('file.gif', 'http://www.x.com/y.gif');
function preloadImages()
{
  if(document.images)
  {
    if(!document.imageArray) document.imageArray = new Array();
    var i,j = document.imageArray.length, args = preloadImages.arguments;
    
    for(i=0; i<args.length; i++)
    {
      if (args[i].indexOf("#")!=0)
      {
        document.imageArray[j] = new Image;
        document.imageArray[j++].src = args[i];
      }
    }
  }
}