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 Web site 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.


var subProtocol = aDataChannel.protocol;


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 ("").


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

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


WebRTC 1.0: Real-Time Communication Between Browsers
# dom-datachannel-protocol

Browser compatibility

BCD tables only load in the browser

See also