#import // https://html.spec.whatwg.org/multipage/comms.html#messageevent [Exposed=(Window,Worker)] interface MessageEvent : Event { constructor(DOMString type, optional MessageEventInit eventInitDict = {}); readonly attribute any data; readonly attribute USVString origin; readonly attribute DOMString lastEventId; // FIXME: readonly attribute MessageEventSource? source; // FIXME: readonly attribute FrozenArray ports; }; dictionary MessageEventInit : EventInit { any data = null; USVString origin = ""; DOMString lastEventId = ""; // FIXME: MessageEventSource? source = null; // FIXME: sequence ports = []; };