Displaying average of dataPoints on Labels in Bar Chart - CanvasJS JavaScript Charts

Displaying average of dataPoints on Labels in Bar Chart - CanvasJS JavaScript Charts

by canvasjs

HTML

<script src="https://canvasjs.com/assets/script/canvasjs.min.js"></script>
<br/><!-- Just so that JSFiddle's Result label doesn't overlap the Chart -->
<div id="chartContainer" style="height: 360px; width: 100%;"></div>

JavaScript

var sum, labels = [];

var chart = new CanvasJS.Chart("chartContainer", {        
  title: {
    text: "Average of Marks"
  },
  data: [
    {
      type: "bar",
      indexLabel: "{y}",
      dataPoints: [
        { label: "Q1", y: 3  },
        { label: "Q2", y: 4  },        
        { label: "Q3", y: 2  }
      ]
    },
    {
      type: "bar",    
      axisYType: "secondary",
      indexLabel: "{y}",
      dataPoints: [
        { label: "Q1", y: 5  },
        { label: "Q2", y: 5  },        
        { label: "Q3", y: 4  }
      ]
    }
  ]
});

updateLabels();
chart.render();

function updateLabels(){
  for(var j = 0; j < chart.options.data[1].dataPoints.length; j++){	
    sum = 0;
    for(var i = 0; i < chart.options.data.length; i++){
      sum += chart.options.data[i].dataPoints[j].y;
    }

    chart.options.data[1].dataPoints[j].label = chart.options.data[1].dataPoints[j].label + " : " + (sum/chart.options.data.length);
  }
}