1. @DomName('Element.getAttributeNS')
  2. @DocsEditable()
  3. @Experimental()
String getAttributeNS(String namespaceURI, String localName)

Source 

@DomName('Element.getAttributeNS')
@DocsEditable()
@Experimental() // untriaged
String getAttributeNS(String namespaceURI, String localName) =>
    _blink.BlinkElement.instance
        .getAttributeNS_Callback_2_(this, namespaceURI, localName);