function result_ajouter_cat(request)
{
if(request.responseText!="vide")
{
$("select_cat_id").innerHTML = request.responseText;
}
}

function ajouter_cat()
{	
	var url = "ajax_new_cat.php";
	var new_value = $("new_cat").value;
	if(new_value!="" && new_value!="Nouvelle categorie") {
	var requete_ajax = new Ajax.Request(
										url,
										{
										"method" : 'POST',
										"parameters" : "new_value="+new_value,
										"onSuccess" : result_ajouter_cat
										}
										);
	} else {
	
	}
	
}