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