.rotation

Number - [only applies to type: "rotation"] The current rotation (in degrees) of the Draggable instance. This is the rotation transform, as in the CSS transform: rotate(...deg). This value is updated each time the Draggable is dragged interactively and during the momentum-based tween that Draggable applies when the user releases their mouse/touch, but if you manually change (or tween) the element’s rotation you can force Draggable to look at the “real” value and record it to its own x property by calling the Draggable’s update() method. Basically that re-synchronizes it. Again, this is not necessary unless other code (outside Draggable) alters the target element’s position.