javascript - how do i pass js variable in the where clause rails 4 -

<div class="field">     <%= f.label :section_id %>          <%= f.select :section_id,options_from_collection_for_select(section.all, :id, :name )%> </div>   <div class="field">      <%= f.label :sub_section_id %>      <div id="sub_section_div"></div> </div>  <div class="actions">       <%= f.submit %> </div>  <script type="text/javascript"> $(document).ready(function(){       $("select#sub_section_section_id").change(function(){           var id_value_string = $(this).val();           **$('#sub_section_div').html('<%= j f.select :name,options_from_collection_for_select(subsection.where(:section_id=>1), :id, :name )%>');**                }); }); </script>  <% end %> 

i have 2 dropdowns section , subsection in view page.when select section want populate respective sub-section. problem want pass id_value_string section_id in clause.please me out.thanks.

it wont work this, can't pass js ruby after page has loaded. think you'd better off using ajax:

$(document).ready(function(){     $("select#sub_section_section_id").change(function(){        var id_value_string = $(this).val();         $.ajax({            url: "<%= sub_sections_path %>",            data: {                section_id: id_value_string            }        });      }); 

you need create new controller/action this, in associated .js view file can line had passing variable sent via ajax:

$('#sub_section_div').html('<%= j f.select :name,options_from_collection_for_select(subsection.where(:section_id=>params[:section_id), :id, :name )%>');