idle-buildup/js/MoneyManager.js

class MoneyManager {
    constructor(startMoney = null) {
        this.money = startMoney ?? this.getSavedMoney();
        return this.saveMoney();
    }

    saveMoney() {
        localStorage.setItem('money', String(this.money));
        return this.getSavedMoney();
    }

    getSavedMoney() {
        this.money = Number(localStorage.getItem('money') ?? 0);
        return this.money;
    }

    add(amount = 0) {
        this.money += amount;
        return this.saveMoney();
    }

    sub(amount = 0) {
        this.money -= amount;
        return this.saveMoney();
    }

    getAmount() {
        return this.money;
    }

    getAmountFormatted() {
        return Intl.NumberFormat('de-DE', {style: 'currency', currency: 'EUR'}).format(this.money);
    }
}