get yLabel value onclick chart js
This demo gives the value in the bar chart when you click on it. I'm not a chart.js expert so there may be better solutions.
https://codepen.io/newschapmj1/pen/PerOzM
/* from https://github.com/chartjs/Chart.js/issues/2292 */
document.getElementById("myChart").onclick = function (evt) {
var activePoints = myChart.getElementsAtEventForMode(evt, 'point', myChart.options);
var firstPoint = activePoints[0];
var label = myChart.data.labels[firstPoint._index];
var value = myChart.data.datasets[firstPoint._datasetIndex].data[firstPoint._index];
alert(label + ": " + value);
};