access the values assigned in javascript via id in select_tag in rails -

i trying access values assigned in javascript in select_tag.

my javascript following:

  function select_pk2(cell){   var val = $('#query_form_opt_'+cell+'_1').val();   var t = $('#query_form_select_ops').val()   var opts = json.parse($('#query_form_select_ops').val());     var pk2 = json.stringify(opts[val]["rows"])   var pk3 = json.stringify(opts[val]["cols"])    $('#query_form_opt_'+cell+'_2').val(pk2)   $('#query_form_opt_'+cell+'_3').val(pk3)     } </script> 

pk2 , pk3 arrays (like pk2 = ["aa","bb"]), expected

<%= select_tag "query_form[opt][#{row}][2]",   :class => "table_column_width_2" %>   <%= select_tag "query_form[opt][#{row}][3]",   :class => "table_column_width_2" %>   

would have values assigned them in javascript, namely pk2 , pk3, somehow not working. how should assigned values select_tag given id (query_form_opt_)?

if want select value in selected box should use value of option. adding options select box should create option element. looks like:

$.each(pk2, function(value) {         $('#query_form_opt_'+cell+'_2')          .append($("<option></option>")          .attr("value", value)          .text(value));    }); 

for select options in select box:

$('#query_form_opt_'+cell+'_2').val(pk2[position_of_option_to_select]) 

hope helps.