Chartjs-Chartjs: Rotate Axis Title

You can do it only one way. And it is that u change in chart.js library.

u should find this part which starts with

if (scaleLabel.display) { in Chart.js and put

var isRight = options.position === 'right';
rotation = isRight ? -0.5 * Math.PI : rotation;

as below

            if (scaleLabel.display) {
                // Draw the scale label
                var scaleLabelX;
                var scaleLabelY;
                var rotation = 0;

                if (isHorizontal) {
                    scaleLabelX = me.left + ((me.right - me.left) / 2); // midpoint of the width
                    scaleLabelY = options.position === 'bottom' ? me.bottom - (scaleLabelFontSize / 2) : me.top + (scaleLabelFontSize / 2);
                } else {
                    var isLeft = options.position === 'left';
                    scaleLabelX = isLeft ? me.left + (scaleLabelFontSize / 2) : me.right - (scaleLabelFontSize / 2);
                    scaleLabelY = me.top + ((me.bottom - me.top) / 2);
                    rotation = isLeft ? -0.5 * Math.PI : 0.5 * Math.PI;
                    var isRight = options.position === 'right';
                    rotation = isRight ? -0.5 * Math.PI : rotation;
                }

                context.save();
                context.translate(scaleLabelX, scaleLabelY);
                context.rotate(rotation);
                context.textAlign = 'center';
                context.textBaseline = 'middle';
                context.fillStyle = scaleLabelFontColor; // render in correct colour
                context.font = scaleLabelFont;
                context.fillText(scaleLabel.labelString, 0, 0);
                context.restore();
            }

as final result