function getHTTPObject() {
   if (window.ActiveXObject) 
      return new ActiveXObject("Microsoft.XMLHTTP");
   else if (window.XMLHttpRequest) 
      return new XMLHttpRequest();
   else {
      return null;
   }
}

function downloadCounter(address) {
   httpObject = getHTTPObject();
   if (httpObject != null) {
      httpObject.open("GET", "download-counter.php?download=" + address, true);
      httpObject.send(null);
   }
}