title: return value from ajax call to javascript
body: <p>I am calling ajax to fetch a value from asp page and return to the calling javascript, and the code is like below</p>
  
  <pre>
  function getNameFromSession()
  {
      xmlhttp=GetXmlHttpObject();
      if (xmlhttp==null)
      {
          alert ("Your browser does not support AJAX");
          return;
      }
      var url="getImageName.asp";
      url=url+"?fetch_name=1";
      xmlhttp.open("GET",url,true);
      xmlhttp.send(null); 
      xmlhttp.onreadystatechange=function(){
  
          if (xmlhttp.readyState==4)
          {
             alert(xmlhttp.responseText);
             return xmlhttp.responseText;
  
          }
  
      }
  }
  
  </pre>
  
  <p>alert in function shows correct value, but javascript get undefined as value, can anybody tell me how can I return the value from this ajax to javascript calling function</p>