chart.jsのPublic APIの getElementAtEvent は getElementsAtEventForMode に変更されている

getElementAtEvent is replaced with chart.getElementsAtEventForMode(e, ‘nearest’, { intersect: true }, true)

function evt_handleChartClick(evt) {
   const points = myChart.getElementsAtEventForMode(evt, 'nearest', { intersect: true }, true);
   if (points.length) {
      const firstPoint = points[0];
      var label = myChart.data.labels[firstPoint.index];
      var value = myChart.data.datasets[firstPoint.datasetIndex].data[firstPoint.index];
      console.log(label +":"+value+":"+firstPoint.datasetIndex+":"+firstPoint.index);
   }
}