RTCSctpTransport: maxMessageSize property

Baseline 2023
Newly available

Since May 2023, this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.

The maxMessageSize read-only property of the RTCSctpTransport interface indicates the maximum size of a message that can be sent using the RTCDataChannel.send() method.

Value

An integer value giving the maximum size, in bytes, of a message which can be sent using the RTCDataChannel.send() method.

Examples

This example shows how you might split up a string into small enough parts to send based on maximum message size.

js
// Function splits strings to a specified size and returns array.
function splitStringToMax(str, maxLength) {
  const result = [];
  let i = 0;
  while (i < str.length) {
    result.push(str.substring(i, i + maxLength));
    i += maxLength;
  }
  return result;
}

const peerConnection = new RTCPeerConnection(options);
const channel = peerConnection.createDataChannel("chat");
channel.onopen = (event) => {
  const maximumMessageSize = peerConnection.sctp.maxMessageSize;
  const textToSend = "This is my possibly overly long string!";
  splitStringToMax(textToSend, maximumMessageSize).forEach((elem) => {
    channel.send(elem);
  });
};

Specifications

Specification
WebRTC: Real-Time Communication in Browsers
# dom-rtcsctptransport-maxmessagesize

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
maxMessageSize

Legend

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Full support
Full support

See also