Rails: access controller instance variable in CoffeeScript or JavaScript asset file

Question

In Rails 3.1 it is not possible to access controller instance variables in an asset js.erb or coffee.erb file using syntax such as <%= @foo %>, where @foo is set in the c

Answer 1

In situations where your javascript data gets out of hand, using the gon gem is still the preferred way to go in rails, even in 2015. After setting up gon, you are able to pass data to your javascript files by simply assigning the data to the gon object in rails.

(Gemfile)
gem 'gon'

(controller) 
def index 
  gon.products = Product.all 

(layouts) 
<%= include_gon %> 

(public/javascripts/your_js_can_be_here.js) 
alert(gon.products[0]['id'); 

(html source automatically produced)