Is there a way to detect Initial pdf?

So, if I have 5 pdf's.  I want a way to only perform an action on the 1st one and not 2, 3, 4, and 5.

I thought maybe there is a method which accesses just the 1st pdf.  I looked through API and saw nothing that helped.

I tried the following but it doesn't work.

var d = app.activeDocs;

for (var i=0; i<d; i++)

for (d==1)

{

app.alert ("it worked")

}