Allows flexible and fast drag/drop functionality. Specifically designed to be performant in these situations:

• Many draggables
• Many droppables
• Draggables and droppables are not fixed collections and may change at any time
• Set of allowed droppables may change depending on what's being drug.

Initially designed to use MooTools, but it can easily be adapted to use any other library or likely to be library agnostic.

All properties shown here are required.

var dragdrop = new Draggables({
   root: any Element that is the common ancestor of all the draggable and droppable elements.
   getDraggable: function(target){
      // This is called on every mouse event.
      // target is the element on which an event happened (mousedown, move, up, ...)
      // If target or one of it's ancestors is draggable, return the element that should be
      // draggable; otherwise, return null and no drag will happen.
   },
   getDroppable: function(target, draggable){
      // This is called while dragging, draggable is the element being drug.
      // target is the element on which an event happened (mousedown, move, up, ...)
      // if target or one of it's ancestors is a drop target, return the element that should
      // act as the drop target; otherwise, return null and no drop event will happen.
   }
);

Draggables fires several events that you can listen to. All of these events have a single argument (event) which is the standard event object from the associated mouse or keyboard event. The event argument also has draggable and droppable properties which are set to the element being dragged and the element that is the current drop target respectively (if applicable)

• dragStart -- Fired as soon as an element is drug more than 10 pixels
• dragInto -- Fired while dragging when the mouse enters into a drop-target
• dragOut -- Fired while dragging when the mouse exits a drop-target
• dragSuccess -- Fired while dragging when the mouse is released on a drop-target
• dragFail -- Fired while dragging when the mouse is released on an non-drop-target
• dragFinish -- Fired after dropFail and dropSuccess, always fires once for every dragStart

To make drag and drop styling of UI elements easier, the class dragOver is added to the element returned from getDroppable while the mouse is over it during a drag event. You can use this to highlight that an area is a valid drop-target.