function getHTTPObject() // Function pour créer l'objet xmlhttprequest //
     {
         var xmlhttp=false;
         try
         {
               xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
         }
         catch (e)
         {
             try
             {
                 xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
             }
             catch (e)
             {
                 xmlhttp = false;
             }
         }
         
         if (!xmlhttp && typeof XMLHttpRequest != "undefined")
         {
             xmlhttp = new XMLHttpRequest();
         }
         return xmlhttp;
     }


function vider_cache(xmlhttp){
  var xmlhttp = xmlhttp;
  xmlhttp.setRequestHeader("Pragma","no-cache");
  xmlhttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
}