Extending nested JS mode in HTML

is it possible to extend what happens in script tags in HTML mode? I’m still a little confused by nested modes. Is it technically possible to push Extensions that only apply to the script tag areas?

I managed to get autocomplete working in a nested mode, but I don’t see examples of how to accomplish other things only in the script areas.

Thanks!

Not extensions, but anything that goes through languageDataAt can be configured per-language, and commands can use isActiveAt to only apply when appropriate.