Thankfully, there is a more elegant solution.
you wrap it in a content_for(:head) (this assumes you have placed a <%= yield :head %> in your application.html.erb template).
<% content_for(:head) do %>
<% end %>
This will place your JS file in the head where it belongs.
For those of you who use jQuery, here is an extra bonus tip.
Sometimes you may want to call in an HTML partial via AJAX (I will write a full tutorial on that later). If you do so using jQuery any script tags that are in the HTML partial will get parsed, loaded and eval(uate)ed automagically. The only caveat is that in this situation you cannot use the content_for(:head) wrapper (and if you call multiple files in this manner the order will matter as the scripts will be launched immediately as opposed to on document.ready).
Using these techniques, you can write discrete web components that encompass both markup and functionality.