Help with adding something to a script

Help with adding something to a script

If this is my script,

if (input.Collected_By  !=  null)
{
    openUrl("#Form:Print_Control?Customer_to_print=" + input.Job_Code, "same window");
}

How do I also add that I want the field 'Print' in print_control to == 'Invoice'

Thanks

Nigel