getMinutelyKey(date) {
        // Truncate value to minutes (e.g. 2021-01-01 12:34:56 -> 2021-01-01 12:34:00)
        date = date.startOf("minute");

        // Convert to timestamp in second
        let divisionKey = date.unix();

        if (! (divisionKey in this.minutelyUptimeDataList)) {
            this.minutelyUptimeDataList.push(divisionKey, {
                up: 0,
                down: 0,
                avgPing: 0,
                minPing: 0,
                maxPing: 0,
            });
        }

        return divisionKey;
    }
Convert timestamp to minutely key
@param {dayjs.Dayjs} date The heartbeat date
@returns {number} Timestamp