JS で列挙をシミュレートする方法

日々を過ごす;
(関数 (日数) {
    days[days["Sunday"] = 0] = "日曜日";
    days[days["Monday"] = 1] = "月曜日";
    days[days["Tuesday"] = 2] = "火曜日";
    days[days["水曜日"] = 3] = "水曜日";
    days[days["木曜日"] = 4] = "木曜日";
    days[days["金曜日"] = 5] = "金曜日";
    days[days["Saturday"] = 6] = "土曜日";
})(日数 || (日数 = {}));

日々を過ごす;
(関数 (日数) {
    days[days["Monday"] = 1] = "月曜日";
    days[days["Tuesday"] = 2] = "火曜日";
    days[days["水曜日"] = 3] = "水曜日";
    days[days["木曜日"] = 4] = "木曜日";
    days[days["金曜日"] = 5] = "金曜日";
    days[days["Saturday"] = 6] = "土曜日";
    days[days["Sunday"] = 0] = "日曜日";
})(日数 || (日数 = {}));

//列挙可能なオブジェクトをエクスポート export EnumWeek = Object.freeze(days)