I'm working with backbone.js models, so I don't know if my question is particular to the way backbone handles cloning or if it applies to javascript in general. Basically, I need to clone a model which has an attribute property assigned an object. The problem is that when I update the parent or clone's attribute, the other model is also updated. Here is a quick example: var A = Backbone.Model.extend({}); var a = new A({'test': {'some': 'crap'}}); var b = a.clone(); a.get('test')['some'] = 'thing'; // I could also use a.set() to set the attribute with the same result console.log(JSON.stringify(a)) console.log(JSON.stringify(b)) which logs the following: {"test":{"some":"thing"}} {"test":{"some":"thing"}} I would prefer to clone a such that b won't be referencing any of its attributes. Any help would be appreciated.