Q:

How do I include a Javascript library in Rails?

I've downloaded a javascript file called jquery.jsPlumb-1.2.6 and placed in my public/javascripts directory.
I want access to this file in one particular html.erb and several js.erbs. What is the best way to do that?

A:

You can either use <%= javascript_include_tag :defaults %> in the HEAD section of your page (recommended): This function will return references to the JavaScript files created by the rails command in your public/javascripts directory. Using it is recommended as the browser can then cache the libraries instead of fetching all the functions anew on every request.
Or you can use<%= javascript_include_tag 'prototype' %>: As above, but will only include the Prototype core library, which means you are able to use all basic AJAX functionality. For the Scriptaculous-based JavaScript helpers, like visual effects, autocompletion, drag and drop and so on, you should use the method described above.
More info here mate.
http://api.rubyonrails.org/classes/ActionView/Helpers/JavaScriptHelper.html

