web api instance property
Location: ancestorOrigins property
The ancestorOrigins read-only
property of the Location interface is a static
DOMStringList containing, in reverse order, the origins of all ancestor
browsing contexts of the document associated with the given Location
object.
You can use location.ancestorOrigins in the script for a document to
determine, for example, whenever the document is being framed by a site which you don’t
expect it to be framed by. You can also use it to vary the behavior of the document
based on what site or list of sites is framing it.
[!NOTE] The
referrerpolicyattribute of an embedding<iframe>affects this list. Settingreferrerpolicytono-referrer, or tosame-originwhen the framed document is cross-origin, redacts the origin of the document containing the<iframe>from theancestorOriginslist of the framed document. The origin is replaced with an opaque origin, which serializes as"null".