Named routes and a Railscast

I'm looking at railscast#102 ( http://railscasts.com/episodes/102-auto-complete-association
) and when I implement it, a certain named
( "formatted_channelnotes_path(:js)" ) route is used in:

<%= text_field_with_auto_complete :channel, :channelnote_name, { :size
=> 15 }, { :url => formatted_channelnotes_path(:js), :method
=> :get, :param_name => 'search' } %>

Which results in:

NoMethodError in Channels#uplog

Showing app/views/channels/_channelnotesfield.html.erb where line #10
raised:

undefined method `formatted_channelnotes_path' for #<ActionView::Base:
0x634b128>

How do I specify this named route? I can see routes specified in my /
config/routes.rb but I don;t understand how I should specify it to
this javascript file. Can someone please show me how to do this?
Thanks, RVince