$('.sortable').sortable().bind 'sortupdate', ->
  $(el_item).each (i, el)->
    cur_index = $(el_item).index(el)
    el_inputs = $(el).find('input[name]')
    el_inputs.each (index, input)->
      original_name = $(input).attr('name')
      changed_name  = original_name.replace(/\[(\d+)\]/, "[#{cur_index}]")
      
      $(input).attr('name', changed_name)