JavaScript Setting for Rails Controller

application.js

// This is a manifest file that'll be compiled into application.js, which will include all the files
// listed below.
//
// Any JavaScript/Coffee file within this directory, lib/assets/javascripts, vendor/assets/javascripts,
// or vendor/assets/javascripts of plugins, if any, can be referenced here using a relative path.
//
// It's not advisable to add code directly here, but if you do, it'll appear at the bottom of the
// compiled file.
//
// WARNING: THE FIRST BLANK LINE MARKS THE END OF WHAT'S TO BE PROCESSED, ANY BLANK LINE SHOULD
// GO AFTER THE REQUIRES BELOW.
//
//= require jquery
//= require jquery_ujs
//= require jquery-ui
// Loads all Bootstrap javascripts
//= require bootstrap

//= require debug
//= require base

//= require_directory .
//= require_tree ./admin

$(function () {
    var $body = $("body");
    var controller = $body.data("controller").replace(/\//, "_");
    var action = $body.data("action");

    var activeController = MyApplication[controller];

    if (activeController !== undefined) {
        if (activeController["common"] !== undefined) {
          activeController["common"]();
        }
        if ($.isFunction(activeController[action])) {
            activeController[action]();
        }
    }
});

debug.js.coffee.erb

<% unless Rails.env.production? %>
# console.log を p で使えるようにする
window.p = (obj) ->
  if window.console
    console.log(obj)
  else
    alert(obj) # IE は alert
  return obj
<% end %>

sample_util.js.coffee

class SampleUtil
  showMessage: ->
    console.log 'show message...'

# ファイルの読み込み順が関わるのであれば、
# application.js で適切な順番に↓を追加する。
# //= require sample_util
# (application.js は上から順に require で指定されたものが読まれます。)

# 呼び出すときは
SampleUtil.showMessage() 

##################################
# もしくは
@MyApplication.showMessage = ->
  console.log 'show message...'

# 呼び出すときは
MyApplication.showMessage()

users.js.coffee

class UsersController
  common: ->
    console.log("UsersController#common index でも show でも UsersController 内のアクションなら表示される")

  index: ->
    console.log("UsersController#index")

  show: ->
    console.log("UsersController#show")

this.MyApplication.users = new UsersController