It's bugged. findAll() can't find all localStorage keys of some Model. In the case, Backbone.LocalStorage requires to use Collection.

clear_backbone_localstorage.coffee

# Clear all data in localStorage about some model class.
@clearLocalStorage = (modelClass) ->
  # Must create a model instance for to sync localStorage.records.
  # (But is also a target that you want to delete it!
  #   Backbone.LocalStorage is not good so much...)
  accessor = new modelClass
  for modelAttrs in accessor.localStorage.findAll()
    target = new modelClass(id: modelAttrs.id)
    accessor.localStorage.destroy target