chart.js v2 tooltip callback title

by Mukesh Yadav

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.1.3/Chart.min.js"></script>
<canvas id="bar-chart" width="600" height="350"></canvas>

JavaScript

// Return with commas in between
  var numberWithCommas = function(x) {
    return x.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");
  };

var dataPack1 = [21000, 22000, 26000, 35000, 55000, 55000, 56000, 59000, 60000, 61000, 60100, 62000];
var dataPack2 = [1000, 1200, 1300, 1400, 1060, 2030, 2070, 4000, 4100, 4020, 4030, 4050];
var dates = ["Mon, May 1", "Tue, May 2", "Wed, May 3", "Thu, May 4", "Fri, May 5", "Sat, May 6", 
  				 "Sun, May 7", "Mon, May 8", "Tue, May 9", "Wed, May 10", "Thu, May 11", "Fri, May 12"];

// Chart.defaults.global.elements.rectangle.backgroundColor = '#FF0000';

var bar_ctx = document.getElementById('bar-chart');
var bar_chart = new Chart(bar_ctx, {
  type: 'bar',
  data: {
      labels: dates,
      datasets: [
      {
          label: 'Bowser',
          data: dataPack1,
          backgroundColor: "rgba(55, 160, 225, 0.7)",
          hoverBackgroundColor: "rgba(55, 160, 225, 0.7)",
          hoverBorderWidth: 2,
          hoverBorderColor: 'lightgrey'
      },
      {
          label: 'Mario',
          data: dataPack2,
          backgroundColor: "rgba(225, 58, 55, 0.7)",
          hoverBackgroundColor: "rgba(225, 58, 55, 0.7)",
          hoverBorderWidth: 2,
          hoverBorderColor: 'lightgrey'
      },
      ]
  },
  options: {
      tooltips: {
        mode: 'label',
        callbacks: {
        title: function(tooltipItems, data) {
          return data.labels[tooltipItems.datasetIndex] + ' ';
        },
        label: function(tooltipItem, data) { 
          return data.datasets[tooltipItem.datasetIndex].label + ": " + numberWithCommas(tooltipItem.yLabel);
        },
       }
      },
      scales: {
        xAxes: [{ 
          stacked: true, 
          ticks: {
            callback: function(value) { return value.substring(5, value.length); },
          },
          gridLines: { display: false },
          }],
        yAxes: [{ 
          stacked: true, 
          ticks: {
            callback: function(value) { return...