I know the original question was asked a few months ago, but I ran into the same problem while working through the Rails engine tutorial, so I'm posting in case this helps others...
I found that I needed to update four files:
1.) add a dependency to your .gemspec file
#file: <your engine name>.gemspec
s.add_dependency "jquery-rails", "~> 3.1.1"
2.) update your engine application.js file:
#file: <your engine name>/app/assets/javascripts/blorgh/application.js
...
//= require jquery
//= require jquery_ujs
//= require_tree .
3.) update your parent app application.js file:
#file: <your engine name>/test/dummy/app/assets/javascripts/application.js
...
//= require jquery
//= require jquery_ujs
//= require_tree .
4.) per this SO thread, you need to add a require to your engine.rb file:
#file: lib/<your engine name>/engine.rb
module <your engine name>
class Engine < ::Rails::Engine
require 'jquery-rails'
isolate_namespace Blorgh
end
end
peace.