Chart.js: Bar Chart Click Events

You can use onClick like this.

var worstCells3GBoxChart = new Chart(ctx, {
                type: 'bar',
                data: {
                    labels: lbls,
                    datasets: [{
                        label: 'Worst Cells by 3G',
                        data: datas,
                        backgroundColor: getColorsUptoArray('bg', datas.length),
                        borderColor: getColorsUptoArray('br', datas.length),
                        borderWidth: 1
                    }]
                },
                options: {
                    legend: {
                        display: false
                    },
                    scales: {
                        yAxes: [{
                            ticks: {
                                beginAtZero: true
                            }
                        }]
                    },
                    onClick: function (e) {
                        debugger;
                        var activePointLabel = this.getElementsAtEvent(e)[0]._model.label;
                        alert(activePointLabel);
                    }
                }
            });

Hi this is the click event under options which is getting values from x and y-axis

onClick: function(c,i) {
    e = i[0];
    console.log(e._index)
    var x_value = this.data.labels[e._index];
    var y_value = this.data.datasets[0].data[e._index];
    console.log(x_value);
    console.log(y_value);
}

I managed to find the answer to my question by looking through the Chart.js source code.

Provided at line 3727 of Chart.js, Standard Build, is the method .getElementAtEvent. This method returns me the "chart element" that was clicked on. There is sufficent data here to determine what data to show in a drill-down view of the dataset clicked on.

On the first index of the array returned by chart.getElementAtEvent is a value _datasetIndex. This value shows the index of the dataset that was clicked on.

The specific bar that was clicked on, I believe, is noted by the value _index. In my example in my question, _index would point to One in chart_config.data.labels.

My handleClick function now looks like this:

function handleClick(evt)
{
    var activeElement = chart.getElementAtEvent(evt);

..where chart is the reference of the chart created by chart.js when doing:

chart = new Chart(canv, chart_config);

The specific set of data that was selected by the click can therefore be found as:

chart_config.data.datasets[activeElement[0]._datasetIndex].data[activeElement[0]._index];

And there you have it. I now have a datapoint that I can build a query from to display the data of the bar that was clicked on.

AUGUST 7TH, 2021. UPDATE

There is now a method for what we are looking for. Take a look at here

I found this solution at https://github.com/valor-software/ng2-charts/issues/489

public chartClicked(e: any): void {
  if (e.active.length > 0) {
  const chart = e.active[0]._chart;
  const activePoints = chart.getElementAtEvent(e.event);
  if ( activePoints.length > 0) {
   // get the internal index of slice in pie chart
   const clickedElementIndex = activePoints[0]._index;
   const label = chart.data.labels[clickedElementIndex];
   // get value by index
   const value = chart.data.datasets[0].data[clickedElementIndex];
   console.log(clickedElementIndex, label, value)
  }
 }
}