//Here's a list of helpful items to capture
var pageURL:String      = ExternalInterface.call('window.location.href.toString');
var pageHost:String     = ExternalInterface.call('window.location.hostname.toString');
var pagePath:String     = ExternalInterface.call('window.location.pathname.toString');
var pageProtocol:String = ExternalInterface.call('window.location.protocol.toString');
var userAgent:String    = ExternalInterface.call('window.navigator.userAgent.toString');
var platform:String     = ExternalInterface.call('window.navigator.platform.toString');
 

private function getQueryString():String
{
     var query:String = ExternalInterface.call("window.location.pathname.toString");
     //ExternalInterface.call("window.location.href.toString");
     return query;
}

Here's how I was able to capture the HREF of a page using actionscript

As3: Capture the HREF, Pathname, Host, userAgent

javascript

ActionScript 3