问Chartjs重叠点击功能不起作用

EN

var canvas = document.getElementById("lineChart");
var ctx = canvas.getContext('2d');


var data = {
  labels: ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"],
  datasets: [{
      label: "Stock A",
      fill: false,
      lineTension: 0.1,
      backgroundColor: "rgba(225,0,0,0.4)",
      borderColor: "red", 
      borderCapStyle: 'square',
      pointBorderWidth: 0.1,
      pointHoverRadius: 6,
      pointHoverBorderWidth: 2,
      pointRadius: 1,
      data: [2, 59, 80, 81, 56],
      spanGaps: false,
      datalabels: {
        enabled: true,
        allowOverlap: true,
        display: true,
        listeners: {
          click: function(context) {
            alert(context.dataIndex + " Red line");
          }
        }
          }
    }, {
      label: "Stock B",
      fill: false,
      lineTension: 0.1,
      backgroundColor: "black",
      borderColor: "black", 
      borderCapStyle: 'square',
      pointBorderWidth: 0.1,
      pointHoverRadius: 6,
      pointHoverBorderWidth: 2,
      pointRadius: 1,
      data: [0, 20, 60, 95, 64],
      spanGaps: false,
      datalabels: {
        enabled: true,
        allowOverlap: true,
        display: true,
        listeners: {
          click: function(context) {
            alert(context.dataIndex + " Black Line");
          }
        }
      }
    }

  ]
};

// Chart declaration:
var myBarChart = new Chart(ctx, {
  showTooltips: false,
  type: 'line',
  data: data
});