Live Streaming temperature and humidity data from a DHT11 though Arduino UNO to plotly

stream_hum_temp.js

// Code inspired from http://adilmoujahid.com/posts/2015/07/practical-introduction-iot-arduino-nodejs-plotly/
// and modified to use multiple traces, using : https://github.com/plotly/plotly-nodejs/blob/master/examples/streaming-multiple-traces.js 

var serialport = require('serialport'),
    plotly = require('plotly')('chintanp','vu32637k4y'),
    tokens = ['xg5vkjdoct', 'qsc0j3pqks'];

var portName = 'COM5';

// serial port part works fine, and was checked independently
var sp = new serialport.SerialPort(portName,{
    baudRate: 9600,
    dataBits: 8,
    parity: 'none',
    stopBits: 1,
    flowControl: false,
    parser: serialport.parsers.readline("\n")
});

// helper function to get a nicely formatted date string
function getDateString() {
    var time = new Date().getTime();
    // 32400000 is (GMT+9 Japan)
    // for your timezone just multiply +/-GMT by 3600000
    var datestr = new Date(time + 19800000).toISOString().replace(/T/, ' ').replace(/Z/, '');
    return datestr;
}
// wanting to create sub-plots with two data-streams 
var initdata = [    
                    {name: "Temperature", x:[], y:[], stream:{token:tokens[0], maxpoints: 1500}}, 
                    {name: "Humidity", x:[], y:[], stream:{token:tokens[1], maxpoints: 1500}}
                ];

var initlayout = {fileopt : "new", filename : "Live Streaming Temperature and Humidity"};

plotly.plot(initdata, initlayout, function (err, msg) {
    if (err)
        return console.log(err)

    console.log(msg);
    
    // creating two streams
    var streams = { 
        "temperature" : plotly.stream(tokens[0], function (err, res) {
            if (err) console.log(err);
            console.log(err, res);
        }), 
        "humidity" : plotly.stream(tokens[1], function (err, res) {
            if (err) console.log(err);
            console.log(err, res);
        }) 
    };

    sp.on('data', function(input) {
        if(isNaN(input) || input > 1023) return;

        var values = input.split('\t');

        // writing the temperature stream
        var tempStreamObject = JSON.stringify({ x : getDateString(), y : values[0] });
        console.log("temperatureObject: " + tempStreamObject);
        streams["temperature"].write(tempStreamObject + '\n');

        // writing the humidiity stream
        var humStreamObject = JSON.stringify({ x : getDateString(), y : values[1] });
        console.log("humidityObject: " + humStreamObject);
        streams["humidity"].write(humStreamObject + '\n');
    });
});