Click trigger on select box doesn't work in jQuery

Question

How can a dropdown list can be opened with a trigger?

Here is the code which doesn't work:

$('select').trigger('click'); 

Just for note - mousedown and mouseup also doesn't work.

Answer 1

$('select').children('option').each(function() {     if ($(this).is(':selected'))     { $(this).trigger('change');  } });