web3.js

const log = console.log;
(async () => {
  const localConnection = new RTCPeerConnection();
  log(localConnection);
  const lsendChannel = localConnection.createDataChannel("sendChannel");
  const remoteConnection = new RTCPeerConnection();
  log(remoteConnection);
  const rsendChannel = remoteConnection.createDataChannel("sendChannel");
  localConnection.onicecandidate = (e) =>
    !e.candidate || remoteConnection.addIceCandidate(e.candidate).catch(log);

  remoteConnection.onicecandidate = (e) =>
    !e.candidate || localConnection.addIceCandidate(e.candidate).catch(log);

  // offer
  const offer = await localConnection.createOffer();
  log(offer);
  await localConnection.setLocalDescription(offer);

  // answer
  await remoteConnection.setRemoteDescription(localConnection.localDescription);
  const answer = await remoteConnection.createAnswer();
  await remoteConnection.setLocalDescription(answer);

  // finish
  await localConnection.setRemoteDescription(remoteConnection.localDescription);
  log(remoteConnection);
})();