I've run into a major problem with jQuery 1.3, but it is only happening with IE7 (not FF3). I have CompanionJS/DebugBar installed on IE, and it catches the errors. I've attached a screenshot showing the errors.

When I load the core library into an iframe with a different URL than the parent page, I get "Access is denied" and other javascript errors. Apparently, the jQuery object fails to get defined as part of the "Access..." error and then other errors cascade from that.

I've got a simple test which basically does nothing but load up the jQuery library into such an iframe. The exact same page can be accessed via two different domains, but the iframe is hardcoded to one of the two domains. So, when the parent page domain is the same as the iframe, jQuery loads fine. But when you create a cross-domain situation, errors ensue (no code changes, just different page domain).

http://flxhr.flensed.com/code/dev-tests/test-jquery-iframe.html (works, because the domains match)

http://www.flensed.com/code/dev-tests/test-jquery-iframe.html (fails with errors)