ThitherHelper.rb

def accumulate_js(key, path)
  javascript_list[key] ||= []
  if path.class == Array || path.class == String
    javascript_list[key] << path
    javascript_list[key].flatten!
    javascript_list[key].uniq!
  else 
    raise ArgumentError
  end
  javascript_list
end

# by extracting the creation of @javascript_list we eliminated dependencies
# the previous code could also have had block variable scope side effects if run in Ruby < 1.9
def include_accumulated_js(order_array, path_hash = javascript_list)
  order_array.map do |key|
    path_hash[key].map do |path|
      javascript_include_tag(path)
    end if path_hash[key]
  end.join
end

private
def javascript_list
  @javascript_list ||= {}
end