ExtendableMessageEvent: ExtendableMessageEvent() constructor

Note: This feature is only available in Service Workers.

The ExtendableMessageEvent() constructor creates a new ExtendableMessageEvent object.


new ExtendableMessageEvent(type)
new ExtendableMessageEvent(type, options)



A string with the name of the event. It is case-sensitive and browsers set it to messageerror or message.

options Optional

An object that, in addition of the properties defined in ExtendableEvent(), can have the following properties:

data Optional

The event's data; this can be any data type. It defaults to null.

origin Optional

A string that defines the origin of the corresponding service worker's environment settings object. It defaults to "".

lastEventId Optional

A string that defines the last event ID of the event source. It defaults to "".

source Optional

The Client, ServiceWorker or MessagePort that sent the message. It defaults to null.

ports Optional

An array containing the MessagePort objects connected to the channel sending the message. It defaults to an empty array.

Return value


const options = {
  data: "hello message",
  source: MessagePortReference,
  ports: MessagePortListReference,

const myEME = new ExtendableMessageEvent("message", init);


Service Workers
# dom-extendablemessageevent-extendablemessageevent

Browser compatibility

BCD tables only load in the browser

See also