creating variable.....?

Hi RoR developers,

I have selection which is not in form object. do you have any idea how
to assign the value of selection to variable.
I want to write something
var select= document.selectionid.value;

is it possible to write ?

and
I have another question which is about params[:id] too.

is it possible call the params[:id] of selection which is not in form
object, from controller,
can we assign it to variable? like

@name=params[:id]

thanks for any commends