#114 Endless Page

Jun 16, 2008 | 8 minutes | Ajax

Ever wondered how some sites seem to have endless scrolling page with no pagination? Find out how easy it is to do this in Rails in this episode.

Click to Play Video ▶

Download:
mp4Full Size H.264 Video (14.3 MB)
m4vSmaller H.264 Video (9.35 MB)
webmFull Size VP8 Video (26.8 MB)
ogvFull Size Theora Video (21.4 MB)

There is a newer version of this episode, see the revised episode.

Alternative Solutions
* Endless Pageless
* Endless Pages Javascript
* Endless Page Plugin

          products_controller.rb
        
def index
  @products = Product.paginate(:page => params[:page], :per_page => 15)
end

          index.js.rjs
        
page.insert_html :bottom, :products, :partial => @products
if @products.total_pages > @products.current_page
  page.call 'checkScroll'
else
  page[:loading].hide
end

          application_helper.rb
        
def javascript(*args)
  content_for(:head) { javascript_include_tag(*args) }
end

          index.html.erb
        
<% title "Products" %>
<% javascript :defaults, 'endless_page' %>

<div id="products">
  <%= render :partial => @products %>
</div>
<p id="loading">Loading more page results...</p>

          endless_page.js
        
var currentPage = 1;

function checkScroll() {
  if (nearBottomOfPage()) {
    currentPage++;
    new Ajax.Request('/products.js?page=' + currentPage, {asynchronous:true, evalScripts:true, method:'get'});
  } else {
    setTimeout("checkScroll()", 250);
  }
}

function nearBottomOfPage() {
  return scrollDistanceFromBottom() < 150;
}

function scrollDistanceFromBottom(argument) {
  return pageHeight() - (window.pageYOffset + self.innerHeight);
}

function pageHeight() {
  return Math.max(document.body.scrollHeight, document.body.offsetHeight);
}

document.observe('dom:loaded', checkScroll);