Mixins are classes that can be included in another class, merging its members (methods and properties) into it. This technique provides us with a form of multiple inheritance where the
mixin class' methods and properties can be accessed as if they were part of the parent class.
By making use of mixins we can package small and reusable bits of functionality into an encapsulated class, and merge it into classes which require that functionality. This reduces repetition and removes the need for the class to be extended directly. One example of a
Mixin used within the framework is the
Ext.form.Labelable class, which gives the component it is mixed into the ability to have a label attached to it.