Defining a backbone model with the singleton pattern. Useful for models that represent things such as the "AppState".

SingletonModel.js

define([
    'underscore',
    'backbone'
], function (_, Backbone) {
    var Singleton = Backbone.Model.extend({

    }, {

        singleton: null,

        getInstance: function() {
            Singleton.singleton = Singleton.singleton || new Singleton;
            return Singleton.singleton;
        }

    });

    return Singleton;

});

// usage
// var model = Singleton.getInstance();