calendarMatrix() {
                function range(start, end) {
                    let ret = [];
                    for (let i = start; i < end; i++) {
                        ret.push(i);
                    }
                    return ret;
                }

                function nulls(count) {
                    return (new Array(count)).fill(null);
                }

                function actualWeekday(day) {
                    return (day + 6) % 7;
                }

                const startDay = new Date(this.year, this.month, 1);
                const endDay = new Date(this.year, this.month + 1, 0);

                const calendarPool = [
                    ...nulls(actualWeekday(startDay.getDay())),
                    ...range(startDay.getDate(), endDay.getDate() + 1),
                    ...nulls(6 - actualWeekday(endDay.getDay())),
                ];

                console.log(calendarPool);

                let calendarMatrix = [];
                for (let step = 0; step < Math.floor(calendarPool.length / 7); step++) {
                    calendarMatrix.push(calendarPool.slice(step * 7, (step + 1) * 7))
                }
                return calendarMatrix;
            }