### 插值算法名称(easing)

* linear
* quadratic\_in
* quadratic\_out
* quadratic\_inout
* cubic\_in
* cubic\_out
* sin\_in
* sin\_out
* sin\_inout
* pow\_in
* pow\_out
* pow\_inout
* circular\_in
* circular\_out
* circular\_inout
* elastic\_in
* elastic\_out
* elastic\_inout
* back\_in
* back\_out
* back\_inout
* bounce\_in
* bounce\_out
* bounce\_inout

具体效果，请参考：[tween.js](http://tweenjs.github.io/tween.js/examples/03_graphs.html)