1_cart.js

define(function(require) {

    var View = require('base/view');
    var menuTemplate = require('hgn!./menu');

    var MenuView = View.extend({

        template: menuTemplate,

        initialize: function(options) {
            this.cart = options.cart;

            this.listenTo(this.cart, 'change', this.render);
        },

        render: function() {
            this.renderTemplate(this.cart.toJSON());
            return this;
        }

    });

    return MenuView;
});

2_view.js

define(function(require) {

    var Backbone = require('backbone');
    var _ = require('underscore');

    var View = Backbone.View.extend({

        renderTemplate: function() {
            var data = _.extend.apply(null, arguments);

            var html = this.template(data);
            this.$el.html(html);

            return this;
        }

    });

    return View;

});