As I have mentioned before recently I have been working quite a bit with some JavaScript frameworks - most heavily with the Prototype JavaScript framework. The main drawback to these frameworks (at the moment) is the scant amount of documentation for them.

I have just come across Justin Palmers look into Enumerable, Array and Hash in Prototype. By exploring the test cases from the source tree he has managed to figure out and demonstrate the power of these features and if you are even slightly tempted by Prototype his article is well worth a read.