The last feature we will implement is the ability to hang up an in-progress call. This will notify the other user of our intention to close the call and stop transmitting information. It will take just a few additional lines to our JavaScript:

hangUpButton.addEventListener("click", function () {
  send({
    type: "leave"
  });

  onLeave();
});

function onLeave() {
  connectedUser = null;
  theirVideo.src = null;
  yourConnection.close();
  yourConnection.onicecandidate = null;
  yourConnection.onaddstream = null;
  setupPeerConnection(stream);
};

When the user clicks on the Hang Up button, it will send a message to the other user and destroy the connection locally. There are a few things required to successfully destroy the connection and also allow another call to be made in the future: