Dynamic Eval of Javascript Functions

I am loading javascript from an external file retrieved via a XMLHttpRequest, but the document.createElement call is returning a Element rather than a HTMLDivElement that I want. (Specifically, the element it is returning has no style member.) I need to figure out a clean way to access the document.

<![CDATA[eval("var func = function() { debug('In function: ' + typeof(document.createElement('div').style)) }");
func();
function Callback(url) {
  this.url = url;
  this.file = url.replace(/.*\//, "");
  var call = function(request) { this.container.callback.call(this.container, request) }
  call.container = this;
  loadXMLDocument(url, call);
}
Callback.prototype = new Function();
Callback.prototype.callback = function(request) {
  if(request.readyState == 4) {
    debug("ID Got: " + this.url + " (" + request.status + ")");
    if(request.status == 200) {
      var functionText = request.responseXML.getElementById('testscript').childNodes[0].data;
      eval("var func = function(filename) { " + functionText + " }");
      func(this.file);
    }
    debugBreak();
  }
}
var url = "text/xml,<code id='testscript'>debug(typeof(document.createElement('div').style))</code>";
//new Callback("data:" + escape(url)); // this doesn't work since data uri's are not supported
new Callback(window.location.pathname);
new Callback(window.location.pathname.replace(/\.[^\.]+$/, ".xml"));

function ArrayCallback(url, pathString) {
  this.url = url;
  this.file = url.replace(/.*\//, "");
  this.path = pathString.split(/:/);
  var call = function(request) { this.container.callback.call(this.container, request) }
  call.container = this;
  loadXMLDocument(url, call);
}
ArrayCallback.prototype = new Function();
ArrayCallback.prototype.callback = function(request) {
  if(request.readyState == 4) {
    debug("Path Got: " + this.url + " (" + request.status + ")");
    if(request.status == 200) {
      var node = request.responseXML;
      for(var i = 0; i < this.path.length; i++) {
        node = node.childNodes.item(this.path[i]);
      }
      var functionText = node.childNodes[0].data;
      eval("var func = function(filename) { " + functionText + " }");
      func(this.file);
    }
    debugBreak();
  }
}
new ArrayCallback(window.location.pathname.replace(/\.[^\.]+$/, ".xml"), "0:1");
new ArrayCallback(window.location.pathname.replace(/\.[^\.]+$/, ".xml"), "0:3");
new ArrayCallback(window.location.pathname.replace(/\.[^\.]+$/, ".xml"), "0:5");]]>