Edit in JSFiddle

var contactData = [
    {firstName: 'John',lastName: 'Doe',phone: '1-111-1111'}, 
    {firstName: 'Jane',lastName: 'Doe',phone: '2-222-2222'},
    {firstName: 'Cody',lastName: 'Lindley',phone: '3-333-3333'},
];

var contacts = new Backbone.Collection(contactData,{model:Backbone.Model});
    
//using where(), returns array with just john and jane models in it from contacts
console.log(contacts.where({lastName:'Doe'}));