Using javascript, there is a confirm statement within an IF statement. The problem is that the confirm statement executes on Form Open. Why?

$(document).ready(function(){

//Check the "Provide Names" box and clear all "Attendee Name(s)" if No
  $('.provideNames input').change(function () {
    if ($(this).val() == "No")
    {
      // clear all Attendee Name(s)
      return 'WARNING:  By selecting "No", the names already inputted will be cleared. Choose OK to clear the names or Cancel to leave as is.';
      $('.attendeeName input').val("")
    }
  });
  $(".provideNames input:checked").each(function(){  
    $(this).trigger('change');
  });

});  //close document.ready