jQuery UI API - Easings

Easing functions specify the speed of an animation at different points. jQuery core comes with two easings: one islinearthe entire animation proceeds at a constant speed; the other isswing(jQuery core's default easing), whose speed is slightly slower at the beginning and end of the animation than in the middle. jQuery UI provides several additional easing functions, ranging from variations on swing behavior to custom effects such as bouncing.

Some easings produce negative values during an animation. Depending on the property being animated, the actual value may be zero. For example, you can setleftto a negative value, but you cannot setheightoropacityto a negative value.

To better understand how an easing affects an animation, spend more time studying the equation graphs. See the graphs of all available animations in jQuery UI listed below.