gistfile1.htm

<select name="add_filter" id="add_filter">
  <option></option>
  <option value="n_ticket" >Nº do ticket</option>
  <option value="priority">Prioridade</option>
  <option value="category">Categoria</option>
  <option value="module">Módulo</option>
  <option value="subject">Título</option>
  <option value="date_sol">Data de solicitação</option>
  <option value="solicitant">Solicitante</option>
  <option value="status">Status</option>
  <option value="percent">Percentual de conclusão</option>
  <option value="available_date">Data de disponibilização</option>
</select>

gistfile2.js

document.observe('dom:loaded', function(){
  if (!$('add_filter')) return;

  var filterMap = {
    n_ticket:         ['t_id'],
    priority:         ['p_id'],
    category:         ['c_id'],
    module:           ['mod'],
    subject:          ['subj'],
    date_sol:         ['date_sol_year', 'date_sol_month', 'date_sol_day'],
    solicitant:       ['sol'],
    status:           ['s_id'],
    percent:          ['percentage'],
    available_date:   ['available_date_year', 'available_date_month', 'available_date_day']
  };
  $('add_filter').observe('change', function(){
    var enable = filterMap[this.getValue()];
    if (enable){
      Effect.toggle(this.getValue(), 'appear');
      enable.each(enable_form);
    }
  });
});