Backbone.js SortableCollection

gistfile1.js

(function (w) {

	w.SortableCollection = Backbone.Collection.extend({
		initialize : function () {
			_.bindAll(this);
		},

		sortInfo : [],

		comparator : function (a, b) {
			for (i = 0; i < this.sortInfo.length; i++) {
				var criteria = this.sortInfo[i];
				var p1 = a.get(criteria.property);
				var p2 = b.get(criteria.property);

				if (p1 < p2) {
					return (-1 * criteria.order);
				}

				if (p1 > p2) {
					return (1 * criteria.order);
				}
			}

			return 0;
		},

		sortBy : function (property) {
			var newSort = [];

			_.each(this.sortInfo, function (field) {
				if (field.property === property) {
					newSort.push({ property : field.property, order : field.order * -1 });
				}
			});

			_.each(this.sortInfo, function (field) {
				if (field.property !== property) {
					newSort.push({ property : field.property, order : field.order });
				}
			});

			this.sortInfo = newSort;
			this.sort();
		}
	});

	w.MySortableCollection = c.SortableCollection.extend({
		sortInfo : [
			{ property : 'Property1', order : -1 }, // descending
			{ property : 'Property2', order : 1 } // ascending
		]
	});

        // implement an instance of the collection
        var sc = new w.MySortableCollection();
        // sort it by a different field...
        sc.sortBy('Property2');

}(this));