The message
event is fired on a MessagePort
object when a message arrives on that channel.
This event is not cancellable and does not bubble.
The message
event is fired on a MessagePort
object when a message arrives on that channel.
This event is not cancellable and does not bubble.
Use the event name in methods like addEventListener()
, or set an event handler property.
js
addEventListener("message", (event) => {}); onmessage = (event) => {};
A MessageEvent
. Inherits from Event
.
This interface also inherits properties from its parent, Event
.
MessageEvent.data
Read only
The data sent by the message emitter.
MessageEvent.origin
Read only
A string representing the origin of the message emitter.
MessageEvent.lastEventId
Read only
A string representing a unique ID for the event.
MessageEvent.source
Read only
A MessageEventSource
(which can be a WindowProxy, MessagePort
, or ServiceWorker
object) representing the message emitter.
MessageEvent.ports
Read only
An array of MessagePort
objects representing the ports associated with the channel the message is being sent through (where appropriate, e.g. in channel messaging or when sending a message to a shared worker).
Suppose a script creates a MessageChannel
and sends one of the ports to a different browsing context, such as another <iframe>
, using code like this:
js
const channel = new MessageChannel(); const myPort = channel.port1; const targetFrame = window.top.frames[1]; const targetOrigin = "https://example.org"; const messageControl = document.querySelector("#message"); const channelMessageButton = document.querySelector("#channel-message"); channelMessageButton.addEventListener("click", () => { myPort.postMessage(messageControl.value); }); targetFrame.postMessage("init", targetOrigin, [channel.port2]);
The target can receive the port and start listening for messages on it using code like this:
js
window.addEventListener("message", (event) => { const myPort = event.ports[0]; myPort.addEventListener("message", (event) => { received.textContent = event.data; }); myPort.start(); });
Note that the listener must call MessagePort.start()
before any messages will be delivered to this port. This is only needed when using the addEventListener()
method: if the receiver uses onmessage
instead, start()
is called implicitly:
js
window.addEventListener("message", (event) => { const myPort = event.ports[0]; myPort.onmessage = (event) => { received.textContent = event.data; }; });
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
message_event |
2 | 12 | 41 | 10 | 10.6 | 5 | ≤37 | 18 | 41 | 11.5 | 4.2 | 1.0 |
messageerror
.
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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/MessagePort/message_event