RTCTrackEventInit.transceiver

The RTCTrackEventInit dictionary's transceiver property specifies the RTCRtpTransceiver associated with the track event. The transceiver pairs the track's receiver with an RTCRtpSender to allow bidirectional communication.

var trackEventInit = {
  receiver: rtpReceiver,
  track: mediaStreamTrack,
  streams: [videoStream],
  transceiver: rtpTransceiver
};

var rtpTransceiver = trackEventInit.transceiver;

The RTCRtpTransceiver which pairs the receiver with a sender and other properties which establish a single bidirectional SRTP stream for use by the track associated with the RTCTrackEvent.