DOM implementations keep track of all NodeIterator objects created for a document, because they may need to modify the state of the NodeIterator when certain Document nodes are deleted. When you are certain that a NodeIterator isn't needed anymore, call detach( ) to tell the implementation that it no longer needs to keep track of it. Note, however, that once you call this method any subsequent call to nextNode( ) or previousNode( ) will throw an exception.
Calling detach( ) is not required, but doing so may improve performance when the document is being modified and the NodeIterator object is not immediately garbage collected.