dropdown values from array

I am javascript dumb and need help. I have an array of Facility ("Facility")and Account # ("Acct"). I want to have the Facility to scroll through the array (new Array1) and Acct to pick up the value

Document JavaScript Selection Array1

var aNamesID = new Array1(

[" ", ""],

["Customer Name One","ID12345"],

["Lower Customer Name Two","ID 789"]

);

this.getField("Facility").setItems(aNamesID);

How do I tie my Selection Field "Facility" to my Array1?

I will have another Selection list / Array doing a similar function (Fields "ProCode" & "Description") do I need to call it "Selection Array2" and

var aNamesID = new Array2(

[" ", ""],

["ItemProCode1","Description of one"],

ItemProCode2","Description of two"]

);

this.getField("Description").setItems(aNamesID2);

thanks