Jim Neath

Manchester based Ruby on Rails & Facebook App Developer

Using jQuery with Ruby on Rails

By default, Rails comes packed with the Prototype javascript library and the effects library, Scriptaculous. While this is all well and good sometimes you want a change. I personally prefer jQuery to prototype. I don’t have any beef with prototype, infact I used it for about a year before even getting into rails, but I just prefer the jQuery syntax and selectors.


jQuery is a fast, concise, JavaScript Library that simplifies how you traverse HTML documents, handle events, perform animations, and add Ajax interactions to your web pages. jQuery is designed to change the way that you write JavaScript.

jQuery, like Protoype, is a javascript library that takes care of much of the grunt work you face day to day. It helps to resolve your cross browser issues, makes creating dom elements easier and various other things.

Some Prototype / jQuery Examples

I’ll post a couple of code examples so you can see the difference in the libraries. I’m not saying these examples are the best way to do things (I know people will say otherwise), they’re just here to help you understand the libraries.

Note: I haven’t tested these examples, although I believe they should all work.


document.observe('dom:loaded', function() {
  $$('a[rel~=external]').invoke('writeAttribute', 'target', 'blank');


$(function() {
  $('a[rel=external]').attr('target', 'blank');

Changes class of a div on click of an element


$('the-link').observe('click', function() {


$('#the-link').click( function() {

For more information on jQuery syntax and all the bells and whistles, have a look at the jQuery Documentation.

More Prototype <=> jQuery Examples

Remy Sharp has also published a walk through comparison between Prototype and jQuery to help developers go from one language to another.

Hello, jRails!

Want to use jQuery but love your prototype helpers too much? Fear not! Enter jRails, stage left.

jRails is a drop-in jQuery replacement for Prototype/script.aculo.us on Rails. Using jRails, you can get all of the same default Rails helpers for javascript functionality using the lighter jQuery library.

That basically says it all.

Installing jRails

ruby script/plugin install http://ennerchi.googlecode.com/svn/trunk/plugins/jrails

Bosh. All sorted. The plugin will install all the required javascript files over to public/javascripts. Unless you’re planning on using prototype along side jQuery you will probably want to delete the prototype files in your javascripts folder.

Including jQuery and Friends

Now you want to open up your application.html.erb file and edit the javascript include tag:

<%= javascript_include_tag :defaults %>

This will now include all the jRails files instead of the prototype/script.aculo.us files. You might want to just include the files that you need instead of all these:

<%= javascript_include_tag 'jquery' %>
<%= javascript_include_tag 'jquery-ui' %>
<%= javascript_include_tag 'jrails' %>

Using jQuery in RJS

You don’t have to do anything. Brilliant. That’s the main point of the jRails plugin. It does all the grunt work for you. Just use your helpers as you normally would.

I will say one thing though: a lot of the time you may just find it easier to use page << at certain times:

page << "$('span#bacon').text('CHunKy');"

jQuery UI

jQuery UI provides abstractions for low-level interaction and high-level, themeable widgets, built on top of the jQuery JavaScript Library, that you can use to build highly interactive web applications.

The core of the library revolves around different mouse interactions, namely drag and dropping, sorting, selecting, and resizing, as well as a powerful set of effects.

On top of the core interactions are built a number of reusable widgets, including accordions, date pickers, dialogs, sliders and tabs.

I was going to write some blurb about jQuery UI but I feel that this quote says it all, really. Want to know more? Check out the jQuery UI site

Some jQuery Scripts

I thought I’d list a couple of helpful scripts to help you on your way to the wonderful world of jQuery. So here goes:


Validation is a great form validation script by Jˆrn Zaefferer. Unobtrusive, sexy and just plain brilliant.


jQuery lightBox plugin is simple, elegant, unobtrusive, no need extra markup and is used to overlay images on the current page through the power and flexibility of jQuery¥s selector.

lightBox is a plugin for jQuery. It was inspired in Lightbox JS by Lokesh Dhakar.

The better way to know what is jQuery lightBox plugin, click the Example tab above and see it in action.

Everybody loves a lightbox, surely? The jQuery Lightbox script is based on by Leandro Vieira Pinho.

If you have any other suggestions for great jQuery scripts, let me know and I’ll add them to the list.

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Jim Neath is a Freelance Ruby on Rails & Facebook app developer from Manchester, UK, currently working for Engine Yard.