The ID of the window. Window IDs are unique within a browser session. In some circumstances a window may not be assigned an ID property; for example, when querying windows using the sessions API, in which case a session ID may be present.
The ID of the window. Window IDs are unique within a browser session. In some circumstances a window may not be assigned an ID property; for example, when querying windows using the sessions API, in which case a session ID may be present.