Change tracking for Backbone models

Backbone.ChangeAwareModel.js

(function () {

  Backbone.ChangeAwareModel = Backbone.Model.extend({

		initialize: function () {
			Backbone.Model.prototype.initialize.apply(this, arguments);

			_.bindAll(this, "mark_to_revert", "revert");

			this.attributesChanged = [];
			this.on("change", this.trackChanges, this);

			return this.mark_to_revert();
		},

		save: function (attrs, options) {
			options || (options = {});

			var self = this,
				value = null,
				success = options.success;

			options.success = function (resp) {
				self.trigger("save:success", self);

				if (success) {
					success(self, resp);
				}

				return self.mark_to_revert();
			};

			this.attributes["_previousAttributes"] = _.pick(this._revertAttributes, _.map(this.attributesChanged, function (value, key, list) { return value.Key; }));
			this.attributes["_changedAttributes"] = _.clone(this.attributesChanged);

			this.trigger("save", this);

			value = Backbone.Model.prototype.save.call(this, attrs, options);

			return value;
		},

		mark_to_revert: function () {
			return this._revertAttributes = _.clone(this.attributes);
		},

		revert: function () {
			if (this._revertAttributes) {
				return this.set(this._revertAttributes, {
					silent: true
				});
			}
		},

		trackChanges: function (model, options) {
			var that = this;

			for (var key in model.changedAttributes()) {
				var modelChange = _.find(that.attributesChanged, function (change) {
					return change && change.Key === key;
				});

				if (modelChange) {
					modelChange.Value = model.get(key);
				} else {
					that.attributesChanged.push({ Key: key, Value: model.get(key) });
				}
			}
		}

	});

})();