How to retrieve responseText in Firefox?

I tried the following code:
var table = new AW.XML.Table;
table.setURL("http://localhost:8080/getresponse");
table.request();
alert(table.getResponseText());
but couldn't get any response in Firefox, it's fine in IE, however.
Then how to get response text in Firefox?

Do you send asynchronous request?

http://www.activewidgets.com/aw.http.request/async.html