var contactA = new Backbone.Model({firstName: 'Luke'});
var contactB = new Backbone.Model({firstName: 'John'});
var contactC = new Backbone.Model({firstName: 'Bill'});
var contactsD = [{firstName: 'Jane'},{firstName: 'Cody'}];
var contacts = new Backbone.Collection([],{model:Backbone.Model});
//add data/attributes object
contacts.add({firstName: 'Jill'});
//add array of data/attributes object
contacts.add(contactsD);
//add model instance
contacts.add(contactA);
//add array of model instances
contacts.add([contactB,contactC]);
//below logs, ["Jill", "Jane", "Cody", "Luke", "John", "Bill"]
console.log(contacts.pluck('firstName'));