I am trying out PeerJS and it works great.
Just looking at the demo's the Peer ID is auto created for you.
Is there a way to define / set your own Peer Id?
Provide a peer id when you create the peer object:
var peer = new Peer('pick-an-id', {key: 'myapikey'});
// You can pick your own id or omit the id if you want to get a random one from the server.
This is right off the page you linked to under Create a peer.