I have to give credit to the authors of the gems I combined and modified to make this a reality:
[jquery-rails-cdn](https://github.com/kenn/jquery-rails-cdn) and [jquery-ui-rails-cdn](https://github.com/styx/jquery-ui-rails-cdn). This gem will utilize [jquery-rails](https://github.com/rails/jquery-rails) however, it will serve your jquery files from the google cdn, if possible, than fall back to your local copies if neccessary.
Serving jQuery from a publicly available [CDN](http://en.wikipedia.org/wiki/Content_Delivery_Network) has clear benefits:
* **Speed**: Users will be able to download jQuery from the closest physical location.
* **Caching**: CDN is used so widely that potentially your users may not need to download jQuery at all.
* **Parallelism**: Browsers have a limitation on how many connections can be made to a single host. Using a CDN for jQuery offloads a big one.
=============
### Features
This gem offers the following features:
* Supports Google CDN
* jQuery version is set in your application.rb file
* Automatically fallback to local jquery min files stored in your vendor directory:
* You're on a development environment, so that you can work offline.
* The CDN is down or unreachable.
On top of that, if you're using asset pipeline, you may have noticed that the major chunks of the code in combined `application.js` is jQuery. Implications of externalizing jQuery from `application.js` are:
* Updating your JS code won't evict the entire cache in browsers.
* Cached jQuery in the client browsers will survive deployments.
* Your code changes more often than jQuery upgrades, right?
* `rake assets:precompile` will run faster and use less memory.
=============
### Installation
If you're using the asset pipeline with Rails 3.1+,
- Start by removing `//= require jquery` from your `application.js` file.
If you're using the asset pipeline with Rails 4+,
- Create the jQuery vendor directory: `mkdir vendor/assets/javascripts/jquery`
- Download the version of jquery you want to use from the [google cdn](https://developers.google.com/speed/libraries/devguide#jquery) and save the file to this directory. The file should look something like `jquery.min.js`.
- Verify you have the jquery-rails gem enabled as well as the new gem:
```ruby
gem 'jquery-rails'
gem 'jquery-rails-google-cdn'
```
- Add these lines to your application.rb file to set the version of jQuery you are using and to make sure the asset pipeline makes it available:
```ruby
config.assets.precompile += ["jquery.min.js"]
config.jquery_version = "2.0.2"
```
- Finally add this section to your layouts file.
```html
<%= jquery_include_tag Rails.application.config.jquery_version %>
<%= javascript_include_tag "application" %>
```
- Please verify you do not have a duplicate `application` js include as this can cause issues with libraries down the road like ember. Here is an example layout of a rails 4 application:
```html
Demoapp
<%= jquery_include_tag Rails.application.config.jquery_version %>
<%= jquery_ui_include_tag Rails.application.config.jquery_ui_version %>
<%= javascript_include_tag "application" %>
<%= stylesheet_link_tag "application", media: "all", "data-turbolinks-track" => true %>
<%= javascript_include_tag "data-turbolinks-track" => true %>
<%= csrf_meta_tags %>
<%= yield %>
```
The gem will generate the following across all modes production, testing, and development:
```html
```
=============
###Changelog
* v0.0.5: Updated Gem Description
* v0.0.4: Bug Fixes
* v0.0.3: Bug Fixes
* v0.0.2: Changed up initial workflow, forking even further from the previous authors
* v0.0.1: Initial release