BetweenJS 介绍
Betweenjs 是一个 JavaScript 的渐变效果实现引擎。
Betweenjs is Tweening Engine for JS.Highly inspired from BetweenAS3.Creates a
Tween and apply it with an immediate effect, accurate for setting desired
values in the time-range of the tween.
BetweenJS 官网
https://github.com/sazaam/BetweenJS
