This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
nodePrincipal returns the
nsIPrincipal object representing current security context of the node.
principalObj = element.nodePrincipal
This property is read-only; attempting to write to it will throw an exception. In addition, this property may only be accessed from privileged code.
Not in any specification.