RTCDataChannel: message event
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since January 2020.
The WebRTC message
event is sent to the onmessage
event handler on an RTCDataChannel
object when a message has been received from the remote peer.
Note: The message
event uses as its event object type the MessageEvent
interface defined by the HTML specification.
This event is not cancelable and does not bubble.
Syntax
Use the event name in methods like addEventListener()
, or set an event handler property.
addEventListener("message", (event) => {});
onmessage = (event) => {};
Event type
A MessageEvent
. Inherits from Event
.
Event properties
Also inherits properties from its parent interface, 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 reference to the message emitter, one of WindowProxy,
MessagePort
, orServiceWorker
. 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).
Examples
For a given RTCDataChannel
, dc
, created for a peer connection using its createDataChannel()
method, this code sets up a handler for incoming messages and acts on them by adding the data contained within the message to the current document as a new <p>
(paragraph) element.
dc.addEventListener(
"message",
(event) => {
let newParagraph = document.createElement("p");
let textNode = document.createTextNode(event.data);
newParagraph.appendChild(textNode);
document.body.appendChild(newParagraph);
},
false,
);
We first create the new paragraph element and add the message data to it as a new text node. Then we append the new paragraph to the end of the document's body.
You can also use an RTCDataChannel
object's onmessage
event handler property to set the event handler:
dc.onmessage = (event) => {
let newParagraph = document.createElement("p");
let textNode = document.createTextNode(event.data);
newParagraph.appendChild(textNode);
document.body.appendChild(newParagraph);
};
Specifications
Specification |
---|
WebRTC: Real-Time Communication in Browsers # event-datachannel-message |
WebRTC: Real-Time Communication in Browsers # dom-rtcdatachannel-onmessage |
Browser compatibility
BCD tables only load in the browser
See also
- WebRTC API
- A simple RTCDataChannel example
- Related events:
open
,close
, anderror
RTCDataChannel.send()