How to use the konva/src/Core.Rect function in konva

initResize() {
    return new Konva.Rect({
      x: this.halfWidth + this.cropRadius * 0.86 - 8,
      y: this.halfHeight + this.cropRadius * -0.5 - 8,
      width: 16,
      height: 16,
      draggable: true,
      dragBoundFunc: function (pos) {
        return {
          x: this.getAbsolutePosition().x,
          y: pos.y
        }
      }
    })
  }

initShading() {
    return new Konva.Rect({
      x: 0,
      y: 0,
      width: this.width,
      height: this.height,
      fill: this.shadingColor,
      strokeWidth: 4,
      opacity: this.shadingOpacity
    })
  }