Object passing by reference in Backbone.Model default values.

gistfile1.js

var TestModel = Backbone.Model.extend({
    defaults: {
        primitiveProp: 'foo',
        objectProp: {
            prop1: 'val',
            prop2: null
        }
    }
});

var model = new TestModel();
var objProp = model.get('objectProp');
objProp['prop2'] = 'bar';
console.log(TestModel.prototype.defaults.objectProp.prop2);
// => 'bar'