Separating days number on weeks

separateDaysByWeek.js

/**
 * Separating days by week with init day setting
 *
 * @param days
 * @param initDay
 * @param initWeekDay
 * @returns {Array[]}
 */
function separateDaysByWeek(days, initDay, initWeekDay = 0) {
    let result = [[]];
    let maxDay = days + initDay;
    let week = 0;
    let weekDays = initWeekDay;

    for (let day = initDay; day < maxDay; day++) {
        result[week].push(day);
        weekDays++;

        if (weekDays === 7) {
            if (day + 1 === maxDay) {
                break;
            }

            week++;
            weekDays = 0;
            result.push([]);
        }
    }

    return result;
}