active_admin.js.coffee

# app/assets/javascripts/active_admin.js.coffee

#= require active_admin/base
ActiveAdmin = {
  dashboard: {},
  user: {}
}

ActiveAdmin.dashboard.index = () ->
  console.log 'Hello'

$(() ->
  controller = $('body').data('controller')
  action = $('body').data('action')
  ActiveAdmin[controller][action]() if ActiveAdmin[controller][action]?
)

layout_hacks.rb

# app/admin/layout_hacks.rb

module ActiveAdmin::Views::Pages::BaseExtension
  def add_classes_to_body
    super
    @body.set_attribute "data-controller", params[:controller].gsub(/^admin\//, '')
    @body.set_attribute "data-action",     params[:action]
  end
end
class ActiveAdmin::Views::Pages::Base
  # mixes in the module directly below the class
  prepend ActiveAdmin::Views::Pages::BaseExtension
end