RTCDataChannel: protocol property

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 read-only RTCDataChannel property protocol returns a string containing the name of the subprotocol in use. If no protocol was specified when the data channel was created, then this property's value is the empty string ("").

Note: The permitted values of this property are defined by the website or app using the data channel.

The ability for each channel to have a defined subprotocol lets your app, for example, use JSON objects as messages on one channel while another channel is plaintext and another is raw binary or even some other format.

Value

A string identifying the app-defined subprotocol being used for exchanging data on the channel. If none has been established, this is an empty string ("").

Example

js
const pc = new RTCPeerConnection();
const dc = pc.createDataChannel("my channel", {
  protocol: "json",
});

function handleChannelMessage(dataChannel, msg) {
  switch (dataChannel.protocol) {
    case "json":
      /* process JSON data */
      break;
    case "raw":
      /* process raw binary data */
      break;
  }
}

Specifications

Specification
WebRTC: Real-Time Communication in Browsers
# dom-datachannel-protocol

Browser compatibility

See also