Cory O'Daniel – These are just words Software development, thoughts, and randomness

<script type="text/javascript" src="http://www.google.com/jsapi?key=INSERT-YOUR-KEY"></script>
<script type="text/javascript">
 google.load("jquery", "1.4.2");
</script>

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>

# Docs: http://code.google.com/apis/ajaxlibs/documentation/index.html
#
class GoogleJsApi
  BaseURL = "http://ajax.googleapis.com/ajax/libs".freeze
 
  Libraries = { 
    "jquery" => {
      :versions => %w(1.2.3 1.2.6 1.3.0 1.3.1 1.3.2 1.4.0 1.4.1 1.4.2),
      :compressed_url => "/jquery/%s/jquery.min.js",
      :uncompressed_url => "/jquery/%s/jquery.js"
    },
    "jqueryui" => {
      :versions => %w(1.5.2 1.5.3 1.6 1.7.0 1.7.1 1.7.2),
      :compressed_url   => "/jqueryui/%s/jquery-ui.min.js",
      :uncompressed_url => "/jqueryui/%s/jquery-ui.js"
    },
    "prototype" => {
      :versions => %w(1.6.0.2 1.6.0.3 1.6.1.0),
      :compressed_url   => "",
      :uncompressed_url => "/prototype/%s/prototype.js"
    },
    "scriptaculous" => {
      :versions => %w(1.8.1 1.8.2 1.8.3),
      :compressed_url   => "",
      :uncompressed_url => "/scriptaculous/%s/scriptaculous.js"
    },
    "mootools" => {
      :versions => %w(1.1.1 1.1.2 1.2.1 1.2.2 1.2.3 1.2.4),
      :compressed_url => "/mootools/%s/mootools-yui-compressed.js",
      :uncompressed_url => "/mootools/%s/mootools.js"
    },
    "dojo" => {
      :versions => %w(1.1.1 1.2.0 1.2.3 1.3.0 1.3.1 1.3.2 1.4.0 1.4.1),
      :compressed_url => "/dojo/%s/dojo/dojo.xd.js",
      :uncompressed_url => "/dojo/%s/dojo/dojo.xd.js.uncompressed.js"
    },
    "swfobject" => {
      :versions => %w(2.1 2.2),
      :compressed_url   => "/swfobject/%s/swfobject.js",
      :uncompressed_url => "/swfobject/%s/swfobject_src.js"
    },
    "yui" => {
      :versions => %w(2.6.0 2.7.0 2.8.0r4),
      :compressed_url   => "/yui/%s/build/yuiloader/yuiloader-min.js",
      :uncompressed_url => "/yui/%s/build/yuiloader/yuiloader.js"
    },
    "ext-core" => {
      :versions => %w(3.0.0 3.1.0),
      :compressed_url   => "/ext-core/%s/ext-core.js",
      :uncompressed_url => "/ext-core/%s/ext-core-debug.js"
    },
    "chrome-frame" => {
      :versions => %w(1.0.0 1.0.1 1.0.2),
      :compressed_url   => "/chrome-frame/%s/CFInstall.min.js",
      :uncompressed_url => "/chrome-frame/%s/CFInstall.js"
    } 
  }.freeze
 
  class << self
    def include(name, version=nil, compressed=true, validate_version=true)
      name = name.to_s
      if lib = GoogleJsApi::Libraries[name]
        version ||= lib[:versions].last
 
        if validate_version && lib[:versions].include?(version)
          GoogleJsApi.url_for(name, version, compressed)
        elsif !validate_version
          GoogleJsApi.url_for(name, version, compressed)
        else
          raise Exception, "Invalid version (#{version}) for #{name}"
        end
      else
        raise Exception, "Unknown Google Javascript Library"
      end
    end
 
    def version_info
      tmp_version = {}
      GoogleJsApi::Libraries.each do |k,v|
        tmp_version[ k ] = v[:versions]
      end
      tmp_version
    end
 
    protected
    def url_for(name, version, compressed)
      GoogleJsApi::BaseURL +
      GoogleJsApi::Libraries[ name ][ compressed ? :compressed_url : :uncompressed_url ] % version
    end
  end
 
end

require 'pp'
 
pp GoogleJsApi.version_info
 
# Include the newest version of a library
puts GoogleJsApi.include('jquery')
 
# Include a specific version of a library
puts GoogleJsApi.include "chrome-frame", "1.0.0"
 
# Include a specific version of a library uncompressed
puts GoogleJsApi.include "chrome-frame", "1.0.0", false
 
# Include a specific version of a library w/o validating the version; useful if this goes out of date :P
puts GoogleJsApi.include "jquery", "NOT_A_VERSION", false, false
 
begin
  puts GoogleJsApi.include :jqueryui, "1.0"
rescue Exception => e
  puts "This should blow up..."
  puts e.message
end

# Rails
require 'google_js_api' #or whatever you named the file when you dropped it in lib
 
# In your application layout or whatever
javascript_include_tag GoogleJsApi.include(:jquery, "1.4.0")

# Merb
require 'google_js_api' #or whatever you named the file when you dropped it in lib
 
#in your application layout or where ever
require_js GoogleJsApi.include(:swfobject)