According to the API documentation of javascript_include_tag
:
Returns an html script tag for each of the sources provided.
You can pass in the filename (.js extension is optional) of javascript files that exist in your public/javascripts directory for inclusion into the current page or you can pass the full path relative to your document root.
You cannot recursively include all files in your directory. However, you always can write something like the next line:
javascript_include_tag *Dir[Rails.root.join("public/javascripts/views/**/*.js")]