[prototype] Element.readAttribute in js.rjs

I am trying to test the 'type' attribute' of some elements in my
page , but I don't get it right,

writing the following code in my .rj.rjs file

page.select('#user-list input').each do |e|
  t = e.readAttribute('type')
  page.alert(t)
end

just displays :

[object HTMLInputElement]

I'm wrong , sure, but why ?

thanks for your suggestions

erwin