http://brandonhilkert.com/blog/organizing-javascript-in-rails-application-with-turbolinks/#comment-2217554683

comments-example.rb

# app/views/posts/show.html.erb
<article id="post-<%= @post.id %>" class="post">
  <h1><%= @post.title %></h1>
  <%= @post.body %>
  <small><%= @post.author %></small>
  <section class="comments">
    <h2>Comments</h2>
    <%= render @post.comments %>
  </section>
</article>

# app/views/comments/_comment.html.erb
<div id="comment-<%= comment.id %>" class="comment">
  <h2><%= comment.author %></h2>
  <%= comment.body %>
  <small><%= comment.author %></small>
  <a href="#" data-behavior="reply">Reply</a>
</div>

# app/assets/javascripts/app.comments.js
App.Comments = {
  reply: function() {
    # ...
  }
};

$(document).on('click', '[data-behavior~=reply]', function(e) {
  App.Comments.reply();
});