ExternalInterface sometimes...others running local

So I'm developing web-based training which will eventually go into a learning management system. When it is in the LMS we will use ExternalInterface and Javascript to communicate with Flash.

But sometimes the same course will need to run locally or perhaps be published to a projector.

I'm using ExternalInterface.available to check if it is available. If it isn't then there is no ExternalInterface available then clearly there will be no LMS communication (the projector version).

But the other bits get tricky. When testing locally in the Flash IDE ExternalInterface.available returns true, but there is nothing to actually interface with.

Any suggestions on how to know if there actually is javascript to help me out and communicate with the LMS?

Thanks.