Skip undefined property in Chart ToolTip - CanvasJS JavaScript Charts

Skip undefined property in Chart ToolTip - CanvasJS JavaScript Charts

by canvasjs

HTML

<script src="https://canvasjs.com/assets/script/canvasjs.min.js"></script>
<div id="chartContainer" style="height: 360px; width: 100%;"></div>

JavaScript

var chart = new CanvasJS.Chart("chartContainer",
                               {
  toolTip:{
    contentFormatter: function (e) {		
      var content = " ";
      for (var i = 0; i < e.entries.length; i++) {
        content += "x:" + e.entries[i].dataPoint.x + " " + "y:" + e.entries[i].dataPoint.y + ((e.entries[i].dataPoint.serial)? "<br/> Serial: " + e.entries[i].dataPoint.serial: "");
      }
      return content;
    }
  }, 
  data: [
    {
      type: "column",
      dataPoints: [
        { x: 10, y: 71, serial: "S01" },
        { x: 20, y: 55, serial: "S02" },
        { x: 30, y: 50 },
        { x: 40, y: 65, serial: "S08" },
      ]
    }
  ]
});

chart.render();