idOf.js

function uid() {
  // Generate a unique and non-colliding id.
  return Math.random().toString(36).slice(2);
}

// Create unique, non-colliding ID namespace.
var __id__ = uid();

function idOf(thing) {
  return (thing && typeof(thing) === ('object' || 'function')) ?
    // If thing is an object or a function, and thing already has an ID,
    // return ID. Otherwise assign an ID.
    (thing[__id__] = thing[__id__] || uid()) :
    // If thing is a primitive, the primitive acts as it's own ID. Return it.
    thing;
}

// @TODO use https://github.com/Gozala/Name to properly shim private names.

In the spirit of http://docs.python.org/2/library/functions.html#id, get a globally unique ID string for any object

Very useful for creating lookup tables.

I'm afraid typeof(null) is "object" so sad JS devs usually do thing && typeof(thing) === "object"

Sneaky JS. Fixed.