Autoupdate jQuery with Rake

After installing jQuery on Rails (jRails) i noticed that the update task just kept overwriting my jquery.js with an older version. Effectively downgrading it…

So here is a real update task, execute it with rake update:jquery

  namespace :update do
    desc "Download recent jQuery javascripts to public/javascripts"
    task :jquery => :environment do
      puts "Downloading files..."
      files = {

      require 'open-uri'
      files.each do |local,remote|
        f = "#{js_dir}/#{local}", 'w' do |f|
          f.write open(remote).read
        puts "downloaded #{local} successfully."
      puts "all files downloaded successfully."

    def js_dir

PS: If the bleeding edge breaks anything you can get your old version back by jrails:update:javascripts

The other jquery libaries(fx,ui) are missing atm, since i am just using jquery on its own. If you know an update site, please drop a comment.

Test Driven Javascript – Aftermath

Yesterday i realesed my first Test Driven Developed jQuery plugin!

For development i used newjs (which has some problems with IE6 atm, but they are sorted out), it comes with a simple unittesting framework and all the assertions and help one can want.


1. Its hard to test, because JS is not designed for test

  • No way to handle alerts/confirms or most of the other user interaction.
  • No sleep method, since javascript has no threads, it is hard to wait for 100ms while a request is performed(luckily jsunit helps with wait)
  • Resetting the DOM is often not possible when you rely on 3rd party code, that just does not bothers with reverting its changes. Normal javascript is one way, executed once and works until the user leaves. The only solution is to split your tests into multiple units, one for every test that involves the 3rd party code. (do the TD community a favour and include a reset method in your next libary)

2. Development takes longer but is rewarded

  • Figuring out ways to test your code and ensuring everything gets resetted takes time and effort
  • Testing against multiple Browsers is where you get your time back! When hacking things to work in IE6 i fell in love with my testsuite 🙂
  • Running tests in multiple browsers is automated by newjs (‘rake test’ will start 6 different browsers and run them over your unit tests)
  • You can keep changing the code without any thought about what this will do to this or that browser.

3. Build a prototype and see it work in every browser

  • Ensure that your approach works with all browsers you want to support
  • Look for workarounds early, so that you can build the right thing, the first time

my unittest source if you want to see it run, download the ‘test and demo packadge’

anything missing ? -> drop a comment 😉