function setup() {

  serial = new p5.SerialPort(); // make a new instance of the serialport library

  serial.on('list', printList); // set a callback function for the serialport list event

  serial.list(); // list the serial ports

}

// get the list of ports:

function printList(portList) {

  // portList is an array of serial port names

  for (var i = 0; i < portList.length; i++) {

    // Display the list the console:

    console.log(i + portList[i]);

  }

}