Ternary if in Javascript with function

Question

I would like to write a ternary if statement in javascript where you call a function and if it returns a value other then 0 set the variable to that value otherwise set it to something else ex:

selectedStartDate = (GetURLParameter("StartDate")) ? 
                     GetURLParameter("StartDate") : 
                     $("#start_date").val();

Is there a way to get rid of the double function call?

Answer 1

selectedStartDate = GetURLParameter("StartDate") || $("#start_date").val();

Answer 2

selectedStartDate = GetURLParameter("StartDate") || $("#start_date").val();

Answer 3

getURLParam = GetURLParameter("StartDate");    
selectedStartDate = (getURLParam ) ? getURLParam  : $("#start_date").val();

Answer 4

Why not just do something like this:

var urlParameter = GetURLParameter("StartDate");
selectedStartDate = urlParameter ? urlParameter : $("#start_date").val();