Backbone.js factory design pattern implementation

Question

I am looking for advice on whether this implementation of a factory design template by the Backbone.js collection is a bad option.

Collections.MyObjects = Backbone.Collection.extend({ model: Models.MyObject }); Collections.MyObjects.getInstance = (function(){ var instances = {}, defaultName = 'default'; return function(name) { name = name || defaultName; if (!instances[name]) { instances[name] = new Collections.MyObjects(); } return instances[name]; }; })(); 

I am looking for alternative implementations and performance / theory optimizations.

Answer 1

Here's an alternative implementation inspired by @ numbers1311407 comments on the question.

 Collections.MyObjects = Backbone.Collection.extend({ model: Models.MyObject }); Collections.MyObjects.instance = (function(){ var instances = {}, defaultName = 'default'; return { "get": function(name) { name = name || defaultName; if (!instances[name]) { instances[name] = new Collections.MyObjects(); } return instances[name]; }, "delete": function(name) { name = name || defaultName; if (!instances[name]) return false; delete instances[name]; return true; } }; })(); 

Not tested.