Can I tell if a frame access will be cross-domain before performing it?

Question

I am trying to find the DOM iframe or frame element for each of the frames in a window's frames collection. The fastest way to do this, I think, is to access the frame's frameElement property. This property is only available for a same-domain access, and returns undefined and prints an error message to the log in the cross-domain case.

I can loop through the elements returned from document.getElementsByTagName to find the correct element in the cross-domain case, but I'd like to avoid printing the "Unsafe JavaScript attempt" message to the log.

Is there any way to tell before trying it if a property access attempt will run afoul of the cross-domain security policy?

Thanks.

Answer 1

You could check the domain on the url of the hosting page and the frame (src property). If the domains differ, you will most likely get an error.

I say most likely because if the frame is on a subdomain, but has specified document.domain to be the same as the parent frame, then cross-domain access will work.