How do I programmatically abort a jQuery drag operation?

Question

How do I programmatically abort a jQuery drag operation?

Using jQuery UI, the user begins a drag operation. While dragging, an asynchronous event occurs that causes the dragged element to be deleted (a timer-based refresh, for example). In the refresh, I would like to do something like this before the refresh to avoid errors from the deleted element :

   element.trigger('dragstop');

But that didn't seem to work.

Answer 1

Officially cancelling a drag while dragging is not allowed in jQuery UI "by design"[1] -- I disagree with the situation, but it is as it is.

If you somewhat reliably want to cancel a drag mid-flight, you will need to combine a couple of hacks [2, 3]:

$( window ).keydown( function( e ){
  if( e.keyCode == 27 ) {
    var mouseMoveEvent = document.createEvent("MouseEvents");
    var offScreen = -50000;

    mouseMoveEvent.initMouseEvent(
      "mousemove", //event type : click, mousedown, mouseup, mouseover, etc.
      true, //canBubble
      false, //cancelable
      window, //event's AbstractView : should be window
      1, // detail : Event's mouse click count
      offScreen, // screenX
      offScreen, // screenY
      offScreen, // clientX
      offScreen, // clientY
      false, // ctrlKey
      false, // altKey
      false, // shiftKey
      false, // metaKey
      0, // button : 0 = click, 1 = middle button, 2 = right button
      null // relatedTarget : Only used with some event types (e.g. mouseover and mouseout).
            // In other cases, pass null.
    );

    // Move the mouse pointer off screen so it won't be hovering a droppable
    document.dispatchEvent(mouseMoveEvent);

    // This is jQuery speak for:
    // for all ui-draggable elements who have an active draggable plugin, that
    var dragged = $('.ui-draggable:data(draggable)')
      // either are ui-draggable-dragging, or, that have a helper that is ui-draggable-dragging
      .filter(function(){return $('.ui-draggable-dragging').is($(this).add(($(this).data('draggable') || {}).helper))});

    // We need to restore this later
    var origRevertDuration = dragged.draggable('option', 'revertDuration');
    var origRevertValue = dragged.draggable('option', 'revert');

    dragged
      // their drag is being reverted
      .draggable('option', 'revert', true)
      // no revert animation
      .draggable('option', 'revertDuration', 0)
      // and the drag is forcefully ended
      .trigger('mouseup')
      // restore revert animation settings
      .draggable('option', 'revertDuration', origRevertDuration)
      // restore revert value
      .draggable('option', 'revert', origRevertValue);
  }
}

Now, this isn't pretty. But it works. Even when canceling while hovering an accepting droppable.

Have fun with it.

[1] - http://bugs.jqueryui.com/ticket/8414
[2] - https://gist.github.com/3517765
[3] - https://forum.jquery.com/topic/how-to-cancel-drag-while-dragging