code: function () {
              var bBox = this.label.getBBox(),
                axis = this.axis,
                horiz = axis.horiz,
                options = axis.options,
                labelOptions = options.labels,
                size = horiz ? bBox.width : bBox.height,
                leftSide = horiz ?
                labelOptions.x - size * { left: 0, center: 0.5, right: 1 }[axis.labelAlign] :
                  0,
                rightSide = horiz ?
                size + leftSide :
                  size;
  
              return [leftSide, rightSide];
          }
docs: Find how far the labels extend to the right and left of the tick's x position. Used for anti-collision
  detection with overflow logic.