NodeJS Serial Port Handler

SerialPortEventHandler.js

//--------------------------------------------------------------------------------
// SERIAL PORT HANDLER
// This module can be imported into nodejs using require method.
// It uses .start(device,baudrate); to create aconnection to the serial hardware
// After that, it manager disconnects to the hardware and retries.
// It employs an array buffer to slow down the processing of incoming commands
// to a speed that your program can handle
//--------------------------------------------------------------------------------
var EventEmitter = require('events').EventEmitter;
var util = require('util');
var serialport = require('serialport');
//--------------------------------------------------------------------------------
// GLOBAL VAR
//--------------------------------------------------------------------------------
var _d = String.fromCharCode(13);
var sp;
var serialInterval;
var buffer = [];
var hold = false;
var spDev, spBaud;
//--------------------------------------------------------------------------------
// MAIN FUNCTION
//--------------------------------------------------------------------------------
var main = function () {
        var self = this;
        console.log('SP MODULE')
        self.start = function (device, baud) {
            spDev = device;
            spBaud = baud;
            sp = new serialport(device, {
                baudrate: baud,
                parser: serialport.parsers.readline(_d)
            });
            sp.on('open', () => {
                self.emit('open');
            });
            sp.on('data', serialdata => {
                buffer.push(serialdata);
            });
            sp.on('close', function () {
                self.emit('close');
            });
            sp.on('error', function (err) {
                self.emit('error',err);
            });
            serialInterval = setInterval(function () {
                if (buffer.length > 0 && hold == false) {
                    hold = true;
                    var cmd = buffer[0];
                    buffer.shift();
                    self.emit('data', cmd);
                    hold = false;
                }
            }, 0);
        };
        self.write = function (str) {
                sp.write(str + _d);
        },
        self.restart = function () {
            if (spDev, spBaud) {
                setTimeout(function () {
                    self.emit('reconnect');
                    self.start(spDev, spBaud);
                });
            }
        }
    }
//--------------------------------------------------------------------------------
// EXPORTS
//--------------------------------------------------------------------------------
util.inherits(main, EventEmitter);
module.exports = main;

//--------------------------------------------------------------------------------
// USAGE EXAMPLE WITHIN YOUR PROGRAM
// In my case, i use CHAR 13 or EOL as terminator to the port, you may elect to 
// change that within the module code above i used [email protected] module
//--------------------------------------------------------------------------------


var port = require('./SerialPortEventHandler.js');
var serialport = new port();

serialport.on('open', function () {
    console.log('port open');
});
serialport.on('data', function (data) {
    // already in String() format, no need to convert a buffer.
    console.log(`serialport data:${data}`);
});
serialport.on('close', function () {
    console.log('port closed');
});
serialport.on('reconnect', function () {
    console.log('port trying to re-establish');
});
serialport.start('COM10', 57600);