Increment and Decrement Firebase Ionic 5

I would like of increment +1 and decrement -1 in database firebase with the simple method

increment() {
      const i = +1;
      this.service.update(i)
}


decrement() {
      const i = -1;
      this.service.update(i)
}

and service I have the simple code

  update(panel: Panel) {
    return this.db.object(`${this.path}/${panel.codeLed}`)
        .update(panel);
  }
  incrementUp(panel: Panel) {
    return this.db.object(`${this.path}/${panel.codeLed}/up`)
        .query.ref.transaction(ups => {
          if (ups === null) {
            return ups = 1;
          } else {
            return ups + 1;
          }
        });
  }