Customizability

The Drag and Drop Feature provides several options to customize the behavior of the drag-and-drop interaction, including several ways to restrict what and when users can drag and drop items.

No reordering

Set the config option canReorder to false, to disable users from being able to choose arbitrary drop locations within a specific item. Drag lines will not be rendered, and can be omitted from the render implementation. Dragging an item between several items will either always target the specific item that is hovered over as new parent, or the parent of the item that is currently being hovered over if the direct hover target is not a folder.

The Drop event described earlier will always contain only an item as target, never childIndex, insertionIndex, dragLineIndex and dragLineLevel.

Limiting which items can be dragged

Implement a canDrag handler that specifies which items can be dragged. This will be called everytime the user tries to start dragging items, and will pass the items to drag as parameter. Returning false in the handler will prevent the drag from starting.

Limiting where users can drop items

Similarly, implement a canDrop handler that specifies where items can be dropped. This will be called everytime the user drags items over a potential drop target (not on every single mousemove event, just when a different drop target is hovered on), and will pass the items to drop and the target as parameters. Returning false in the handler will prevent the drop from finalizing and calling the onDrop method, as well as visually indicating that the drop is not allowed at that location.

Note that this doesn't concern dragging foreign data inside, which can be controlled with canDropForeignDragObject instead.