var po = 0;
var co = 0;

function changeOffer(panelNum, offer) {
   if (document.getElementById("po" + po)) {
      var panel = document.getElementById("po" + po);
      var pa = panel.getElementsByTagName("a");
      if (offer) {
         jQuery("#po" + po).fadeOut(function () {
            for (var i = 0; i < pa.length; i++) {
               pa[i].href = offer.url;
            }
            pa[1].innerHTML = offer.desc;
            panel.getElementsByTagName("img")[0].src = offer.i;

         });

         jQuery("#po" + po).fadeIn(function () {
            po++;
            co++;

            if (po === 4) {
               po = 0;
            }

            if (co === offers.length) {
               co = 0;
            }

            setTimeout(function () { changeOffer(po, offers[co]); }, 2500);

         });
      }
   }
}