JavaScript syntax question: conditional list element?

[wdt]

This is probably an easy one for you Javascript wonks...

I'm looking for a way to conditionally include or exclude a list element -- in Perl this is easy, how's it done in Javascript?

x = dosomething("yadda", (sometest() ? "yep" : ()), "blah");

So if sometest() returns TRUE then then we dosomething("yadda","yep","blah") otherwise we dosomething("yadda","blah").

Is that possible in Javascript?