The current y (vertical) position of the Draggable instance. So for a Draggable of
type:"x,y", it would be the
y transform translation, as in the css
type:"top,left", the Draggable's
y would refer to the css
"top" value that's applied. This is not the global coordinate - it is the inline css-related value applied to the element. 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 position you can force Draggable to look at the "real" value and record it to its own "y" 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.