An Object.observe shim (use Object.observe = new ObjectObserver;)

ObjectObserver.js

ObjectObserver = function() {
        var objects   = []
          , cache     = []
          , callbacks = [];

        var compare = function(obj, old, change) {
                var newObj = {};

                for(var i in obj) {
                        if(obj.hasOwnProperty(i)) {
                                if({}.toString.call(obj[i]) === "[object Object']") {
                                        newObj[i] = clone(obj[i], old[i]);
                                } else if({}.toString.call(obj[i]) === '[object Function]') {
                                        if(obj[i].toString() === old[i].toString()) {
                                                change(obj[i]);
                                        }
                                        newObj[i] = obj[i].toString();
                                } else {
                                        if(obj[i] !== old[i]) {
                                                change(i, obj[i]);
                                        };
                                        newObj[i] = obj[i];
                                }
                        }
                }

                return newObj;
        };

        setInterval(function() {
                for(var i = 0, j=objects.length; i < j; i++) {
                        cache[i] = compare(objects[i], cache[i], function(i) {
                                return function() {
                                        for(var k = 0, l = callbacks[i].length; k < l; k++) {
                                                callbacks[i][k].apply(objects[i],arguments);
                                        }
                                }
                        }(i));
                }
        }, 0);

        return function(obj, callback) {
                 var exists;

                 if(!callback) throw new Error("You must provide a callback");

                 for(var i = 0, j = objects.length; i < j; i++) {
                         if(obj ===objects[i]) {
                                 exists = true;
                                 callbacks[i].push(callback);
                         }
                 }

                 if(!exists) {
                         objects.push(obj);
                         cache.push(obj);
                         callbacks.push([callback]);
                 }
        };
};