Question Regarding Plugin and Javascript for MS crm 2011

I have a plugin for entity A ie create Pre plugin and it will update entity B's one Rec and I use Service.update(B).

Now as of now I have entity B and I have created update Pre plugin on it.

My question is will this plugin on entity B will be trigerred when I use entity A

Also what I create Javascript for entity B onSave. Again will my plugin on entity A will Trigger this JavaScript on Plugin B