If you want to extend App.reset() in your EmberJS application, you need to make sure that you extend the prototype of App, rather than the creation of your specific App. That is, instead of:
App = window.App = Ember.Application.create LOG_TRANSITIONS: true # NOTE will not work! reset: -> @_super() App.isEmbedded = null
You need to define both a prototype (which can access @_super()) and the creator:
# we need to extend so it's available to each instance of the class AppPrototype = Ember.Application.extend reset: -> @_super() App.isEmbedded = null App = window.App = AppPrototype.create LOG_TRANSITIONS: true
Otherwise you will get App is not defined errors. See also Understanding Ember.Object.