JavaScript hashmap equivalent

Question

As made clear in update 3 on this answer, this notation:

var hash = {};
hash[X]

does not actually hash the object X; it actually

Answer 1

This looks like a pretty robust solution: https://github.com/flesler/hashmap

It will even work well for functions and objects that look identical. The only hack it uses is adding an obscure member to an object to identify it. If your program doesn't overwrite that obscure variable (it's something like hashid), you're golden.