function handleClick(e) {
            let [mouseX, mouseY] = getMousePosition(e);
            let dataPoint = isHorizontal ? getNearestDataPoint2(mouseY) : getNearestDataPoint(mouseX);

            dispatcher.call('customClick', e, dataPoint, d3Selection.mouse(e));
         }
Click handler, passes the data point of the clicked bar
(or it's nearest point)
@private