XML mulitple value script

Presently I am trying to figure out a task.

I am looking to use muitiple values to initiate an action.

ie Check box
if(this.rawValue == 1)
Infopg3.infoa4.presence = "visible";
else
Infopg3.infoa4.presence = "hidden";
 
xfa.layout.relayout();

However I am looking for a direction on using the check box to read a field in a drop down menu to initiate a "visible" task.

Any thoughts ??