javascript error in internet explorer

[atul singh]

Hi,
I wanted to know about preCallHandlers in wicket-ajax.js .What are they and
How are they related in java code.
Actually I am facing a problem in internet explorer. The ajax get call give
error after "Invoking pre-call handler(s).."
It gives an error in the highlighted portion and then all ajax stops
working, because this get call did not return.
The error says--"invalid argument"
I will really appreciate any help. Also if anyone know a javascript
debugger/debugging technique for internet explorer, please let me know, so i
will be able to do something about this :(..

Thanks


    doGet: function() {
        if (this.precondition()) {

            this.transport = Wicket.Ajax.getTransport();

            var url = this.createUrl();
            this.log("GET", url);

            Wicket.Ajax.invokePreCallHandlers();

          *  var t = this.transport;**
            if (t != null) {
                if (Wicket.Browser.isGecko()) {
                    var href = document.location.href;
                    var lastIndexOf = href.lastIndexOf('/');
                    if (lastIndexOf > 0)
                    {
                        url = href.substring(0,lastIndexOf+1) + url;
                    }
                }
                t.open("GET", url, this.async);
                t.onreadystatechange = this.stateChangeCallback.bind(this);
                // set a special flag to allow server distinguish between
ajax and non-ajax requests
                t.setRequestHeader("Wicket-Ajax", "true");
                t.setRequestHeader("Wicket-FocusedElementId",
Wicket.Focus.lastFocusId || "");
                t.setRequestHeader("Accept", "text/xml");
                t.send(null);
                return true;*
            } else {
                this.failure();
                   return false;
            }
        } else {
            Wicket.Log.info("Ajax GET stopped because of precondition check,
url:" + this.url);
            this.done();
            return true;
        }
    }