Flash做动画时会用到Tween类，利用它可以做很多动画效果，例如缓动、弹簧等等。

这里利用flash的Tween类的算法，来做js的Tween算法，并利用它做一些很炫的缓动效果。 -Flash animation will be used to do the Tween class, which allows you to do a lot of animation effects, such as easing, springs, and so on. Tween class here to use the flash algorithm to do the Tween js algorithm, and use it to do some fancy easing effect.