b-tween
A simple but powerful tweening engine for Javascript.
缓动方式：
linear
quadIn
quadOut
quadInOut
cubicIn
cubicOut
cubicInOut
quartIn
quartOut
quartInOut
quintIn
quintOut
quintInOut
sineIn
sineOut
sineInOut
bounceIn
bounceOut
bounceInOut
缓动时间：
开始
重置