Node setNamedItemNS(Node arg) throws DOMException;
arg
The node to be added to the NamedNodeMap.
The node that was replaced, or null if no node was replaced.
This method throws exceptions for the same reasons as setNamedItem( ). It may also throw a DOMException with a code of NOT_SUPPORTED_ERR if it is called in an implementation that does not support XML documents or XML namespaces.
This method works like setNamedItem( ), except that the node added to the NamedNodeMap can later be looked up by its namespaceURI and localName properties instead of by its nodeName property. This method is useful only with XML documents that use namespaces. Note that this method may be unsupported (i.e., may throw an exception) in implementations that do not support XML documents.