How to use the jsts/org/locationtech/jts/operation/buffer.BufferOp function in jsts

buffer(width) {
    const parser = new OL3Parser();
    parser.inject(
      Point,
      LineString,
      LinearRing,
      Polygon,
      MultiPoint,
      MultiLineString,
      MultiPolygon,
    );

    const features = this.selectInteraction.getFeatures().getArray();
    for (let i = 0; i < features.length; i += 1) {
      const jstsGeom = parser.read(features[i].getGeometry());
      const bo = new BufferOp(jstsGeom);
      const buffered = bo.getResultGeometry(width);
      features[i].setGeometry(parser.write(buffered));
    }
  }