HTML
Living Standard — Last Updated 2 April 2024
Living Standard — Last Updated 2 April 2024
The WebSocket interface used
to be defined here. It is now defined in WebSockets. [WEBSOCKETS]
MessageEvent interfaceSupport in all current engines.
Messages in server-sent events, cross-document messaging,
channel messaging, broadcast channels, and WebSockets use
the MessageEvent interface for their message
events: [WEBSOCKETS]
[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 = []);
};
dictionary MessageEventInit : EventInit {
any data = null;
USVString origin = "";
DOMString lastEventId = "";
MessageEventSource? source = null;
sequence<MessagePort> ports = [];
};
typedef (WindowProxy or MessagePort or ServiceWorker) MessageEventSource;event.dataSupport in all current engines.
Returns the data of the message.
event.originSupport in all current engines.
Returns the origin of the message, for server-sent events and cross-document messaging.
event.lastEventIdSupport in all current engines.
Returns the last event ID string, for server-sent events.
event.sourceSupport in all current engines.
Returns the WindowProxy of the source window, for cross-document
messaging, and the MessagePort being attached, in the connect event fired at
SharedWorkerGlobalScope objects.
event.portsSupport in all current engines.
Returns the MessagePort array sent with the message, for cross-document
messaging and channel messaging.
The data
attribute must return the value it was initialized to. It represents the message being sent.
The origin attribute must return the value it was
initialized to. It represents, in server-sent events and cross-document
messaging, the origin of the document that
sent the message (typically the scheme, hostname, and port of the document, but not its path or
fragment).
The lastEventId attribute must return the value it
was initialized to. It represents, in server-sent events, the last event ID string of the event source.
The source attribute must return the value it was
initialized to. It represents, in cross-document messaging, the
WindowProxy of the browsing context of the Window object
from which the message came; and in the connect events used by shared workers, the newly connecting
MessagePort.
The ports
attribute must return the value it was initialized to. It represents, in cross-document
messaging and channel messaging, the MessagePort array being
sent.
The initMessageEvent(type, bubbles,
cancelable, data, origin, lastEventId,
source, ports) method must initialize the event in a manner
analogous to the similarly-named initEvent() method.
[DOM]
Various APIs (e.g., WebSocket, EventSource) use the
MessageEvent interface for their message event
without using the MessagePort API.