Scope of XML Retrieval Functions

function createRequest() {
  var request;
  if(typeof(XMLHttpRequest) != "undefined") {
    request = new XMLHttpRequest();
  } else if (window.ActiveXObject) {
    var msxmlProgids = new Array("MSXML2.XMLHTTP.5.0", "MSXML2.XMLHTTP.4.0", "MSXML2.XMLHTTP.3.0",
                                 "MSXML2.XMLHTTP", "Microsoft.XMLHTTP");
    for(var i = 0; (i < msxmlProgids.length &&
                    typeof(request) == "undefined"); i++) {
      try { request = new ActiveXObject(msxmlProgids[i]); } catch(e) { }
    }
  }
  return request;
}

function requestURL(request, url, asynchronous) {
  asynchronous = typeof(asynchronous) != "undefined" ? asynchronous : true;
  try {
    request.open("GET", url, asynchronous);
    request.send(null);
  } catch(e) {
    debug("For: \"" + url + "\": " + e);
  }
}

var scopeTestFunction = function() {
  var scope = "unknown";
  if(this == window) { scope = "window"; }
  else if(this == arguments.callee) { scope = "callee"; }
  else { scope += " (" + this + ")"; }
  debug("Scope of callback: " + scope + " [" + this.userData + "]");
}
scopeTestFunction.userData = "user data";

var request = createRequest();
request.onreadystatechange = scopeTestFunction;
requestURL(request, window.location.pathname);

var nestingCallback = function() {
  arguments.callee.callback.apply(arguments.callee.callback, arguments);
}
nestingCallback.callback = scopeTestFunction;

request = createRequest();
request.onreadystatechange = nestingCallback;
requestURL(request, window.location.pathname);