Since jquery is packaged with Rails 3.0, I'm using the jquery-ui-rails gem to get jquery-ui.
Looks like jquery_ujs is not packaged with Rails (or jquery-ui-rails). And I can't independently include jquery_ujs gem (there is no such gem, it is packaged with the jquery-rails gem ... which specifically states that I don't need this gem if I'm on Rails 3.0+).
I try to require jquery_ujs in my application.js but obviously it's not found.
So how do I get jquery_ujs?!
If you're including the jquery-rails gem in your Gemfile, then jquery-ujs is already installed. Simply make sure it's added to your application.js manifest like so:
//= require jquery
//= require jquery-ujs
And if you also have jquery-ui-rails, you can then add a manifest entry for that:
//= require jquery.ui.all
gem 'jquery-rails' in your Gemfile that Rails had put there by default. You should absolutely include that gem if you're using jquery, unless you want to install a specific version of the jquery.js and jquery-ujs.js files manually.
gem 'jquery-rails' by default. And it's pointless anyways, as there is no manifest for javascript. The asset pipeline, which uses the manifests, was introduced in Rails 3.1. @RingoBlancke probably came up with the best solution.