Backbone.js

// Collection save

Backbone.Collection.prototype.save = function (options) {
            // create a tmp collection, with the changed models, and the url
            var tmpCollection = new Backbone.Collection( this.changed() );
            tmpCollection.url = this.url;
            // sync
            Backbone.sync("create", tmpCollection, options);
        };
        Backbone.Collection.prototype.changed = function (options) {
            // return only the changed models.
            return this.models.filter( function(m){
                return m.hasChanged()
            });
        };
// and sync the diffs.
self.userCollection.save();