Easy javascript inclusion in Rails

If, like me, you don’t like big cumbersome javascript files, and you’d rather load only the javascript you need right this minute, this little hack might help you.

In application_helper.rb :
# local javascript for a certain page; this will only appear if this tag is called
 def use_local_javascript(local_javascript)
  content_for :local_javascript do
    javascript_include_tag local_javascript
  end
 end


Then, in the <head/> in your layout, you put the following:
<%= yield :local_javascript %>

Instead of multiplying layouts, you just call the helper on top of your pages, say:
<% use_local_javascript("just_magic.js") %>
(needless to say ‘just_magic.js’ should exist in /public/javascripts/

It’s not nuclear science, but it allows you to split your javascript into small manageable bits, and include it only when you need, without multiplying layouts.