[davedx]

* BackboneJS

* UnderscoreJS

[muriithi]

Both have annotated source code

http://backbonejs.org/docs/backbone.html

http://underscorejs.org/docs/underscore.html

http://chrisawren.com/posts/Learning-Advanced-JavaScript-via...

[rubiquity]

I"m not sure why this is being downvoted, other than the fact they are JavaScript codebases. JAshkenas did a wonderful job on these two libraries and they are incredibly well documented.