this.filterCarts = this.userCarts.filter(
      cart => {
        var out = true;
        if (out === true && this.filter.cefr !== null) {
          out = cart.cefrKey === this.filter.cefr;
        }
        if (out === true && this.filter.typeId !== null) {
          out = cart.typeId === this.filter.typeId;
        }
        if (out === true && this.filter.letter !== null) {
          out = cart.letter === this.filter.letter;
        }
        return out;
      });