What is a Mixin?

In this screencast I implement and use a Mixin with stock JavaScript / ES2015 (ES6):

"In object-oriented programming languages, a Mixin is a class that contains methods for use by other classes without having to be the parent class of those other classes (...)":

See you at Single Page Applications (SPAs) -- the "no frameworks, no migrations" approach, at Munich Airport, Terminal 2 or webstandards.training (online).