Thanks Mikal,
Thanks WackyToaster - and to answer your question: if I understand that other thread correctly, you're asking about collision filtering for non-physics objects? For LFJS, I'm trying to make an-almost-complete port of Box2D with Liquidfun - at least as complete as it can be when accessed through C3 (and later for C2). So the collision filtering in LFJS will have no effect on anything that is not inside LFJS. So maybe 'no'.
However, if you're interested in a Physics alternative with bespoke collision filtering then: yes, LFJS will have full Box2D collision filtering via Collision Mask, Collision Filter and Collision Index. It will also include a Pre-Solve trigger where you will be able to enable/disable a particular collision that the filters don't cover (If you're that way inclined!). Does that answer your question?