Organize js files in rails

app assets javascripts application.js.es6

import Flash from "components/flash";

export default function() {
  // called all the times
  Flash.dismiss();
}

export edit function() {
  // called in any edit action
}

app assets javascripts components flash.js.es6

export default {
  allElements: function() {
    return $("#flash_notice, #flash_alert");
  },
  dismiss: function() {
    var self = this;
    setTimeout(function() {
      self.allElements().fadeOut("slow");
    }, 3000)
  }
}

app assets javascripts main.js

//= require jquery
//= require jquery_ujs
//= require jquery.turbolinks
//= require turbolinks
//= require loader
//= require_tree .

$(function() {
  var route = $('body').data("route");
  var controller = route.controller;
  var action = route.action;

  callModule("application", action);
  callModule(controller, action);

  // Lookup a file with the name of the controller and call the exported functions named "default" 
  // and the current action name
  //
  // For instance, given a controller named users, and an action edit, the following is called: 
  //
  // require("application")["default"]();
  // require("application")["edit"]();
  // require("users")["default"]();
  // require("users")["edit"]();

  function callModule(controller, action) {
    if(!(controller in require._eak_seen)) { return }

    var module = require(controller);

    ["default", action].forEach(function(method) {
      if(typeof module[method] === "function") {
        module[method]();
      }
    });
  }
});

app assets javascripts users.js.es6

export default function() {
  // called all the times when the users controller is used
}

export edit function() {
  // called in any edit action of users controller
}

app views layout application.html.slim

doctype 5
html lang="pt"
  head
    meta charset="utf-8"
    meta name="keywords" content=""
    meta name="description" content=""

    title
      = page_title(app_name: 'pirtub')

    link href="/favicon.ico" rel=("shortcut icon")

    = stylesheet_link_tag 'application', media: 'all', 'data-turbolinks-track' => true
    /Use main.js as entry point
    = javascript_include_tag 'main', 'data-turbolinks-track' => true
    = csrf_meta_tags

    /![if lt IE 9]
      script src="http://html5shim.googlecode.com/svn/trunk/html5.js"

  /Pass the current controller and action so we can get it in the js
  body class=body_class data-route="#{ { controller: controller_name, action: action_name }.to_json }"

    = render 'header'

    = render 'flash_messages'

    = yield

    = render 'footer'

config initializers assets.rb

Rails.application.config.assets.version = '1.0'
Rails.application.config.assets.precompile += %w( main.js ) # include main.js in the asset pipeline

Gemfile.rb

# ...
gem 'jquery-turbolinks' # for not bother with vendor plugins not loading
gem 'es6_module_transpiler-rails' # to use es6 modules
# ...