all.js.erb

---
compressed: false
---
// Put this file in your javascripts directory
// Iterate over the items in the project and concatenate the javascripts that are marked for compression.
<% for js_item in @items.select {|i| i.identifier =~ %r{^/javascripts/}} -%>
<% next unless js_item.attributes.fetch(:compressed, true) -%>
<%= js_item.rep_named(:default).compiled_content %>
<% end -%>

Rules.rb

# Don't compile the javascripts
compile '/javascripts/*/' do
  nil
end

# Don't route the javascript that is compressed,
# otherwise route to a js file instead of an index.html
route '/javascripts/*/' do
  if item[:compressed]
    nil
  else
    item.identifier.chop+".js"
  end
end