This mixin implements Observer-friendly Array-like behavior. It is not a concrete implementation, but it can be used up by other classes that want to appear like arrays.
For example, ArrayProxy is a concrete classes that can be instantiated to implement array-like behavior. Both of these classes use the Array Mixin by way of the MutableArray mixin, which allows observable changes to be made to the underlying array.
Ember.Enumerable, this mixin defines methods specifically for
collections that provide index-ordered access to their contents. When you
are designing code that needs to accept any kind of Array-like object, you
should use these methods instead of Array primitives because these will
properly notify observers of changes to the array.
You can use the methods defined in this module to access and modify array
contents in a KVO-friendly way. You can also be notified whenever the
membership of an array changes by using
Ember.Array in your own class, you must override two
primitives to use it:
Note that the Ember.Array mixin also incorporates the
Ember.Array-like objects are also enumerable.