The way you import serialport changed in version >= 10:

Below you have two equivalent examples to import serialport module.

Solution #1

var sp = require('serialport')

sp.SerialPort.list()
.then((data) => console.log(data))
.catch(err => console.log(err));

Solution #2

const {SerialPort} = require('serialport')

SerialPort.list()
.then((data) => console.log(data))
.catch(err => console.log(err));

For reference, it's stated here: https://serialport.io/docs/guide-upgrade#exports

list is a property of the serialport module, and not of serialport.SerialPort. Replace the first lines like this:

var serialport = require("serialport");
var SerialPort = serialport.SerialPort;
var util = require("util"), repl = require("repl");

serialport.list(function (err, ports) {
  ports.forEach(function(port) {
    console.log(port.comName);
    console.log(port.pnpId);
    console.log(port.manufacturer);
  });
});

Javascript is inherently asynchronous. What is happening is that the console.log is executing before the serial ports can be listed. The library provides a callback (which you are using) and a promise. Either of these can be used to make sure things run in order. I recommend promises.

const SerialPort = require('serialport');

SerialPort.list() // returns promise that resolves to list of ports
    // filters for a specific port
    .then(ports => ports.filter(port => port.pnpId == "USB\\VID_0451&PID_BEF3&MI_00\\6&808E38E&0&0000"))
    // logs info
    .then(ports => {console.log('inner',port[0].comName, 'outer', port[0]); return ports})