jQuery on CDN - Usage Stats

Dave Ward has done an informal study on the top 200,000 sites identified by Alexa to find which of those sites use a public jQuery CDN. His findings:

• 47 of the Alexa top 1,000 include a Google CDN reference.
• 99 of the Alexa top 2,000 reference jQuery on the Google CDN.
• 6,953 of the top 200,000 sites include a script reference to some version of jQuery hosted on Google’s CDN.
• 989 of the Alexa top 200,000 sites reference jQuery UI on the Google CDN.

Dave recommends keeping your site’s CDN reference updated to the latest compatible version of jQuery for more performance gains. This is because popular sites generally upgrade to the latest stable version & sites must reference exactly the same CDN URL in order to obtain the cross-site caching benefit.

Google CDN hosts:

• jQuery (versions 1.2.3, 1.2.6, 1.3.0, 1.3.1, 1.3.2, 1.4.0, 1.4.1)
• jQuery UI (versions 1.5.2, 1.5.3, 1.6.0, 1.7.0, 1.7.1, 1.7.2, 1.7.3, 1.8.0, 1.8.1, 1.8.2, 1.8.4) 
• File to reference looks like this - http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js

Microsoft Ajax CDN hosts:

• jQuery (versions 1.3.2, 1.4, 1.4.1, 1.4.2)
• jQuery Validation library (versions 1.5.5, 1.6, 1.7)
• jQuery UI 1.8.5
• File to reference looks like this - http://ajax.microsoft.com/ajax/jQuery/jquery-1.3.2.min.js
• File to reference looks like this - http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.3.2.min.js

As per the BuiltWith.com website (which tracks technology usage trends), nearly 37% of the top 10,000 sites currently use jQuery in any form (not just from the CDN)

10/Sept/2013 Update: The jQuery UI files follow this pattern:

// Google

Uncompressed: http://ajax.googleapis.com/ajax/libs/jqueryui/[UI.VERSION]/themes/[THEME-NAME]/jquery-ui.css

Minified: http://ajax.googleapis.com/ajax/libs/jqueryui/[UI.VERSION]/themes/[THEME-NAME]/jquery-ui.min.css

// Microsoft

Uncompressed: http://ajax.aspnetcdn.com/ajax/jquery.ui/[UI.VERSION]/themes/[THEME-NAME]/jquery-ui.css

Minified: http://ajax.aspnetcdn.com/ajax/jquery.ui/[UI.VERSION]/themes/[THEME-NAME]/jquery-ui.min.css

List of  CDN-hosted jQuery UI Themes

Also see:
jQuery Tips, Tricks, Trivia
Web apps in less than 10 KB
Popular JavaScript apps dissected