ReadonlyhtmlDOM element of the underlying LayerItem, undefined if the toc has been disposed
or if the item is currently not being rendered.
ReadonlyidIdentifier of the Toc item.
Currently, this is the same as layerId, but that could be changed in the future.
Readonlyistrue if list item is expanded.
Optional ReadonlylayerIdentifier of the layer that corresponds with the list item. May be undefined if the item does not represent a layer.
Expands or collapses the list item.
Note: not all list items support this operation.
Optionaloptions: ExpandItemOptions
Represents an item in the toc.
Currently items register themselves in the model when they are mounted and remove themselves when they are unmounted.