MessageEvent: MessageEvent() constructor

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨August 2016⁩.

Note: This feature is available in Web Workers.

The MessageEvent() constructor creates a new MessageEvent object.

Syntax

new MessageEvent(type)
new MessageEvent(type, options)

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

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

data Optional: The data you want contained in the MessageEvent. This can be of any data type, and will default to null if not specified.
origin Optional: A string representing the origin of the message emitter. This defaults to an empty string ('') if not specified.
lastEventId Optional: A string representing a unique ID for the event. This defaults to an empty string ("") if not specified.
source Optional: A MessageEventSource (which can be a Window, a MessagePort, or a ServiceWorker object) representing the message emitter. This defaults to null if not set.
ports Optional: An array of MessagePort objects containing all MessagePort objects sent with the message, in order. This defaults to an empty array ([]) if not specified.

const myMessage = new MessageEvent("message", {
  data: "hello",
});

Specification
HTML # the-messageevent-interface:dom-event-constructor

This page was last modified on ⁨Oct 29, 2024⁩ by MDN contributors.