void detach( ) throws DOMException;
Like all Range methods, detach( ) throws a DOMException with a code of INVALID_STATE_ERR if it is called on a Range object that has already been detached.
DOM implementations keep track of all Range objects created for a document, because they may need to change the range boundary points when the document is modified. When you are certain that a Range object isn't needed any more, call the detach( ) method to tell the implementation that it no longer needs to keep track of that range. Note that once this method has been called for a Range object, any use of that Range will throw an exception. Calling detach( ) is not required but may improve performance in some circumstances when the document is being modified and a Range object is not subject to immediate garbage collection.