Q:

CDNs that host javascript libraries (ie. CodeMirror)

Do you guys know of CDNs that let you load JavaScript libraries from, the way that Google does with jQuery and a few others.
I'm looking for one that hosts CodeMirror library.

A:

looks like no one, but you can vote for Google to take care about it, hopefully they would implement it:
Add Codemirror to Libraries API

A:

Codemirror is hosted on cdnjs.com.

