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.

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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.

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);
});

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);
};