I went through episode 88 (Dynamic menus) of the railscasts and when I try to load my *js.erb file in the browser shows me that my fetched data from the controller is getting there

Controller

 def dynamic_departments
    @departments = Department.all
 end

localhost:3000/javascripts/dynamic_departments.js

  var departments = new Array();
  departments.push(new Array(1,'????',1));
  departments.push(new Array(2,'???-???',2));

  function facultySelected(){   
  faculty_id = $('falculty_id').getValue(); 
  options = $('department_id').options;
  options.length = 1;
  departments.each(function(department){
     if(department[0] == faculty_id){
        options[options.length] = new Option(department[1],department[2])
     }
  });

  if(options.length == 1){
    $('department_field').hide();
  } else {
     $('department_field').show();
   }
}

  document.observe('dom:loaded', function(){
     alert("DOM loaded");   
     //$('department_field').hide();
     //$('faculty_id').observe('change',facultySelected);
   });

My routes.rb has the match ':controller/:action.:format' Still...after the page's loaded and I change the value of my collection_select or select nothing happens.What am I missing?

*I called the 'alert' and commented the rest to test it....still nothing.