datachannel.js

    (function() {
      var
        // Configuration:
        hostname = window.CHANNEL_HOST || window.location.hostname || 'localhost',
        websocketServer = "ws://"+hostname+":8000/",
      
        // For browser compatibility:
        PeerConnection = window.PeerConnection 
                      || window.RTCPeerConnection 
                      || window.mozPeerConnection 
                      || window.webkitRTCPeerConnection 
                      || window.webkitPeerConnection00;

      if (typeof(PeerConnection) === 'undefined') {
        console.error('Your browser does not support PeerConnection.');
        return;
      }

      var pc = new PeerConnection(null);

      if (typeof(pc.createDataChannel) !== 'undefined') {
        try {
          // This will throw when data channels is not implemented properly yet
          pc.createDataChannel('polyfill')

          // If we get this far you already have DataChannel support.
          return;
        } catch(e){
          // TODO verify the Error
        }
      }

      function DataChannel(peerConnection,label,dataChannelDict) {
        this.label = label;
        this.reliable = dataChannelDict && dataChannelDict.reliable;
        this._peerConnection = peerConnection;

        this._webSocket = new WebSocket(websocketServer);
        this._webSocket.onclose = function() {
          // Do something!
        }

        this.readyState = "connecting";

        this._webSocket.onopen = function() {
          this.readyState = "open";
          this._identify();
        }.bind(this);

        this._webSocket.onmessage = function(msg) {
          if (typeof this.onmessage == 'function') {
            this.onmessage(msg);
          }
        }.bind(this);
      };

      DataChannel.prototype._identify = function() {
        if (this._peerConnection === null) return false;

        function description2id(description) {
          var result = description.sdp.replace(/(\r\n|\n|\r)/gm, '\n')
          var re = new RegExp("o=.+");
          result = re.exec(result)
          return result[0]
        }

        if (this._peerConnection._localDescription && this._peerConnection._remoteDescription) {
          this.send('connect:' 
            + description2id(this._peerConnection._localDescription) + '_' + this.label + ':' 
            + description2id(this._peerConnection._remoteDescription) + '_' + this.label);
        }
      };

      DataChannel.prototype.close = function() {
        this._webSocket.close();
      };

      DataChannel.prototype.send = function(data, onErrorCallback) {
        if( this.readyState == 'open' )
          this._webSocket.send(data, onErrorCallback);
      };

      PeerConnection.prototype.createDataChannel = function(label, dataChannelDict) {
        var channel = new DataChannel(this,label,dataChannelDict);

        if (typeof(this._allDataChannels) == 'undefined') {
          this._allDataChannels = [];
        }
        this._allDataChannels.push(channel);

        return channel;
      }

      // Overwrite PeerConnection's description setters, to get ID:s for the websocket connections.

      var
        setLocalDescription = PeerConnection.prototype.setLocalDescription,
        setRemoteDescription = PeerConnection.prototype.setRemoteDescription;

      PeerConnection.prototype.setLocalDescription = function(description) {
        this._localDescription = description;
        if (typeof(this._allDataChannels) != 'undefined') {
          for (var i in this._allDataChannels) {
            this._allDataChannels[i]._identify();
          }
        }
        setLocalDescription.call(this, description);
      };

      PeerConnection.prototype.setRemoteDescription = function(description) {
        this._remoteDescription = description;
        if (typeof(this._allDataChannels) != 'undefined') {
          for (var i in this._allDataChannels) {
            this._allDataChannels[i]._identify();
          }
        };
        setRemoteDescription.call(this, description);
      };

    }());