Javascript + DOM in your ruby, the simple way
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Latest commit dc80bd2 Jul 6, 2010 @mynyml v0.5.6


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Harmony provides a simple DSL to execute javascript + DOM code within ruby.


Simple Javascript Parsing

require 'harmony'

page =<<-HTML)

page.execute_js("1+1")            #=> 2
page.execute_js("document.title") #=> "Foo"

The Page object's #execute_js method (aliased as #x for convenience) takes a string of javascript code, executes it and returns the last statement's value (just like a ruby method).

Javascript Unit Tests

One interesting use of Harmony is to test your javascript code within your ruby application's own tests (test/unit, minitest, RSpec, nanotest, etc). Which consequently means that you can now run browser-less, fully command-line based, DOM-javascript tests.

require 'test/unit'
require 'harmony'

class JavascriptTest < Test::Unit::TestCase
  def setup
    @page =

  def test_foo
    assert_equal "world", @page.execute_js(<<-JS)
      foo = new Foo;

DOM Handling

Don't be affraid to throw in your favorite client-side js framework, like JQuery or Prototype. And notice that scripts linked to in <script> tags will automatically get pulled in.

require 'harmony'

page =<<-HTML)
      <script src="javascripts/jquery.js" type="text/javascript"></script>
      <div id="widget">ohaie</div>

page.execute_js("$('#widget').innerHTML") #=> "ohaie"

Fetching Documents

Use Harmony::Page.fetch(uri) to create a page from a remote document.

require 'harmony'

page = Harmony::Page.fetch('')
page.execute_js('document.title') #=> "Example Web Page"

fetch also accepts "file://" uris.


# There's a gem dependency bug in rubygems currently, so we'll have to
# install some dependencies manually. This will be fixed soon.
gem install stackdeck
gem install johnson -v "2.0.0.pre3"

gem install harmony

See Also


Harmony is a thin DSL wrapper around three amazing libs, Johnson, env.js and Envjs . The authors of those libs have been doing a huge amount of great work for quite a while, so please go recommend them on WorkingWithRails right now and/or follow them on github:

jbarnette, tenderlove, smparkes, wycats, matthewd, thatcher, jeresig

Special thanks go to smparkes for his patient help, and for providing the last puzzle pieces that made everything work together.


YinYang ASCII art is © Normand Veilleux (nveilleuATemr1.emrDOTca)