Variable in Funktion aufrufen

[Divi]

<script type="text/javascript">
  var xmlhttp;
  var info_carrier = "";

function call_slideshow(__item_id) {
   test = get_user_images(__item_id);
   alert(info_carrier); // Rückgabe ""
  }

function get_user_images(__item_id) {
   url = "<?php echo TEAM_MEMBER_INFO_PREFIX; ?>" + __item_id;

// code for Mozilla, etc.
   if (window.XMLHttpRequest) {
    xmlhttp = new XMLHttpRequest();
    xmlhttp.onreadystatechange=xmlhttpChange;
    xmlhttp.open("GET",url,true);
    xmlhttp.send(null);
   }
   // code for IE
   else if (window.ActiveXObject){
    xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
    if (xmlhttp) {
     xmlhttp.onreadystatechange = xmlhttpChange;
     xmlhttp.open("GET",url,true);
     xmlhttp.send(null);
    }
   }

return true;
  }

function xmlhttpChange() {
   // if xmlhttp shows "loaded"
   info_carrier = "";

if (xmlhttp.readyState==4) {
    // if "OK"
    if (xmlhttp.status==200) {
     info_carrier = xmlhttp.responseText;
     alert(info_carrier); // 2 Zeilen die aus der Datei ausgelesen wurden
    }
   }

return true;
  }
 </script>