gistfile1.txt

(function(){
  $('#demand_receiver_department').on('change', function(){
    var employee = $("#demand_receiver_user");
    $.getJSON('/employees.json?by_department='+$(this).val(), function(data){
      employee.empty();
      employee.append('<option value="">Selecione</option>');
      $.each(data, function(i,item){
        employee.append('<option value="' + item.id + '">' + item.name + '</option>');
      });
    });
  });
})();