move multiple option in select with jQuery

I look for this everywhere: how to move multiple option inside a select function upfield() { var el = $(‘#selectedfield’).children(‘[@selected]:first’).prev(); $(“#selectedfield”) .children(‘[@selected]’) .each(function(){ $(this).insertBefore(el); }); } function downfield() { var el = $(‘#selectedfield’).children(‘[@selected]:last’).next(); $(“#selectedfield”) .children(‘[@selected]’) .each(function(){ $(this).insertAfter(el); el = $(el).next(); }); }