Why Refactor Tween.js?

IMO (@unstoppableCarl) Tween.js abstracted away almost all important implementation details making it impossible to implement advanced usage. It was designed (seemingly on purpose) to not be extendable / flexible.

For a game I am working on I needed a tweening library

Requirement	Tween.js	Needs
Performant Tweening	Yes	Yes
Easing	Yes	Yes
Interpolation	Yes	Yes
Work in nodejs / browserify	No	Yes
Simple to extend	some callbacks but only passed target object as param, no prototype use on objects	tween object, target, and progress
Performant config	config settings set with chainable functions	in a game loop so many extra functions cost to much performance.
Tween config object	chainable setters, cannot read them after they are set	portable and composable tween settings readable after setting
Separation of tween objects and update queue	tightly coupled, tween objects add and remove themselves from a global queue	efficient game loop
Multiple update queues	No	Yes
Observe the internal state of tween	No	debugging

Despite all of these problems Tween.js was simple enough that I could refactor it to meet my needs and it is pretty reliable and battle tested.