Insulate 
"Page-specific JavaScript and CSS".
Easily partition your JavaScript and CSS based on controller actions. Works great with Rails' default asset pipeline configuration (i.e. all JavaScript and CSS concatenated into application.js and application.css respectively). Generally recommended only for small Rails applications where you have a direct one-to-one mapping between controller actions and views, and don't mind introducing a little coupling.
Installation
Add this line to your application's Gemfile:
gem 'insulate'And then execute:
$ bundle installUsage
This gem automatically injects a global JavaScript string variable, INSULATE_PAGE, into every page served by your app. This string is always in the format controller#action, so if you want to conditionally execute some JavaScript code based on the current controller action, just check the value of this variable.
JavaScript example:
if (INSULATE_PAGE == 'users#edit') {
alert('Edit an existing user!');
}CoffeeScript example:
if INSULATE_PAGE is 'users#new'
alert 'Create a new user!'Furthermore, this gem also appends a special CSS class to the <body> element of every page. The name of this class changes dynamically based on the current controller action, and is always in the format insulate-page-controller-action. So for example, if the controller action is users#show, the name of the class will be insulate-page-users-show. You can easily segregate your stylesheet markup by targeting this class in CSS selectors.
CSS example:
.insulate-page-users-show h1
{
color: red;
}
.insulate-page-users-show p
{
color: blue;
}LESS example:
.insulate-page-users-show
{
h1
{
color: red;
}
p
{
color: blue;
}
}Contributing
My intention with this gem is to keep it as simple and lean as it currently is, so do keep that in mind when submitting pull requests. If you want more advanced functionality, it's worth having a look at Paloma, an excellent gem that provides a much more comprehensive page-specific JavaScript solution.