[nostrademons]

It was very undivided 8 years ago - it was common knowledge to never, ever override the prototypes of built-in objects. In fact, a major reason that JQuery won out over Prototype & Mootools was because the latter two monkey-patched built-in prototypes, and as a result were incompatible with each other or with any other library that overrode built-in methods.

IIRC, this was an interview question at Google when I applied in 2008, and I think one of the reasons I got the job was because I was aware of all of the pitfalls of it.

I managed to skip using underscore, but from a quick glance through the library, isn't the reason it's called underscore because it provides '_' as a namespace for all the utility functions, rather than altering Array.prototype the way Prototype did?

[hyperpape]

I read the underscore source code a few years ago. My memory may be failing me, but I don't think it altered any builtins.