Function startOf

code/gmane/Chart.bundle.js:3601–3642

(units)

    }

    function startOf (units) {
        units = normalizeUnits(units);
        // the following switch intentionally omits break keywords
        // to utilize falling through the cases.
        switch (units) {
        case 'year':
            this.month(0);
            /* falls through */
        case 'quarter':
        case 'month':
            this.date(1);
            /* falls through */
        case 'week':
        case 'isoWeek':
        case 'day':
            this.hours(0);
            /* falls through */
        case 'hour':
            this.minutes(0);
            /* falls through */
        case 'minute':
            this.seconds(0);
            /* falls through */
        case 'second':
            this.milliseconds(0);
        }

        // weeks are a special case
        if (units === 'week') {
            this.weekday(0);
        }
        if (units === 'isoWeek') {
            this.isoWeekday(1);
        }

        // quarters are also special
        if (units === 'quarter') {
            this.month(Math.floor(this.month() / 3) * 3);
        }

        return this;
    }

    function endOf (units) {
        units = normalizeUnits(units);