Must stay up all night and develop first DataChannel based P2P BitTorrent style file sharing implementation tonight..
It's the only one I've seen that abides to the bittorrent spec (where possible). BEP 9 and 10 support incoming.
(Demo's broken, need to push a fix :()
Also note that currently DataChannels do not support reliable transfer and have a small MTU, so sending enormous files does not yet work. With PeerJS you can send smaller files, but larger ones will take an unreasonable amount of time.
It's written with PeerJS, by one of the other creators of PeerJS, same as OP.