Definition
HTML Standard defines MessageEvent
[Exposed=(Window,Worker,AudioWorklet)]
interface MessageEvent : Event {
constructor(DOMString type, optional MessageEventInit eventInitDict = {});
readonly attribute any data;
readonly attribute USVString origin;
readonly attribute DOMString lastEventId;
readonly attribute MessageEventSource? source;
readonly attribute FrozenArray<MessagePort> ports;
undefined initMessageEvent(DOMString type, optional boolean bubbles = false, optional boolean cancelable = false, optional any data = null, optional USVString origin = "", optional DOMString lastEventId = "", optional MessageEventSource? source = null, optional sequence<MessagePort> ports = []);
};