code: function scaleX(_scaleX) {
      var scaleY = this.imageData.scaleY;
      return this.scale(_scaleX, isNumber(scaleY) ? scaleY : 1);
    }
docs: Scale the image on the x-axis.
  @param {number} scaleX - The scale ratio on the x-axis.
  @returns {Cropper} this