Assuming the CDN provider has an https version, you can use protocol-relative URLs.
For example, instead of:
http://ajax.googleapis.com/ajax/libs/jquery/1.4/jquery.min.js
...you can use:
//ajax.googleapis.com/ajax/libs/jquery/1.4/jquery.min.js
The browser will use the page's protocol to try to obtain the file. On non-secure pages, http. On secure pages, https.
Google also makes YUI Loader available through its CDN. So for YUI this works fine:
//ajax.googleapis.com/ajax/libs/yui/2.8.0/build/yuiloader/yuiloader-min.js
...in both http and https contexts.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…