When you login as Host in DotNetNuke 5 or greater, you will have access to jQuery settings on the Host Settings screen. Using these settings allows you to configure the jQuery library which will be used in the framework.
The settings allows hosts to specify which version of the jQuery library they wish to use. This allows hosts to have greater control over their environment. Just remember that the core and some third party modules may have version dependencies so you should be careful about pointing to older versions of the scripts.
By default, DotNetNuke will use the minified version of jQuery that is served from the DotNetNuke resources directory. This configuration provides good performance while also minimizing external dependencies. For those looking to maximize their performance, we have included support for using a hosted version of jQuery. The default hosted jQuery version will be the minified version hosted on Google. By using a hosted version of the library, you increase the likelihood that the user will already have a cached version of the library.
The default shipped settings are NOT optimal. The default version number of 1 (see graphic below) asks for the currently latest available version. This is unwise. Google serves the latest available version with no cache control headers,
actively preventing caching of the library. In addition, the jQuery code served for your site may change without warning.
Hosts should update the URL to the version number they used to test the site. Google serves numbered versions with far future expiring cache headers, allowing the library to be cached.
Hosts should consider removing the protocol (http:/https:) prefix. The browser will issue the request using the same protocol as used for the hosting page. Removing the http/https prefix means that in on http page you get the best performance, on an https page you avoid warnings about mixed secure/insecure content. Here is an example recommended URL for jQuery
//ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js
jQuery UI Host Settings
As of DotNetNuke 6, jQuery UI is also included with the framework. The host settings area also has options for loading jQuery UI, just like the loading of jQuery itself.
The discussion above; about caching, version numbers and protocols also applies to jQueryUI.
You can see a sample of the settings in the image below: