MochiKit is a platform-agnostic javascript framework that doesn't suck. (Here's the release announcement , following the announcement of a public subversion repository a few days ago.) The documentation alone should make MochiKit the preferred js library. It's a huge improvement over the alternatives. Bob Ippolito has been working on MochiKit for a while. I've learned a lot from his javascript blog posts as he's worked on it. If you think you know javascript, but don't know what a prototype is (I didn't), you need to read his blog. (Yes, Bob knows about JSoLait and Prototype. He doesn't like them , and gives excellent reasons for the genesis of MochiKit.)