Pianista

# posts_controller.rb
class PostsController < ApplicationController
  def index
    @posts = Post.paginate(page: params[:page], per_page: 3)
    respond_to do |format|
      format.html
      format.js
    end
  end
end

# index.html
<div class="page-header">
  <h1>My posts</h1>
</div>

<div id="my-posts">
  <%= render @posts %>
</div>

<div id="more_posts">
  <%= link_to "More posts...", posts_index_url(page: @posts.next_page), remote: true %>
</div>

# index.js.erb

$("#my-posts").append('<%= escape_javascript render(@posts)%>');
$("#more_posts").html('<%= escape_javascript(link_to("More posts...", posts_index_url(page: @posts.next_page), remote: true)) if @posts.next_page %>');

# _post.html.erb

<div>
  <h2><%= post.title %></h2>

  <small><em><%= post.created_at %></em></small>

  <p><%= truncate(strip_tags(post.body), length: 600) %></p>
</div>