I just wanna know what is the best data structure type or any idea for executing multiple promo codes for discounts in the right order. For example I may have $164.99 worth of items in my shopping basket. After I apply promo code that takes 5% off the initial price and then I apply -20 dollars promo code I get 136.74 as the final price. Now let's say I wanna switch the order promotions have been added to the basket. On the initial price of $164.99 I first want to apply -20 dollars promo code and then 5% promo code and I get the 137.74 as the final price. How can I make it always have the right price in this case it would be $136.74 let's say.

I've only applied one switch case for that and here it is :

export const priceAfterDiscount = (cart, promotions) => {
let totalReturnedPrice = getCartTotal(cart);
promotions.forEach(element => {
    switch(element){
    case "5%OFF":
        var reducedPrice = (totalReturnedPrice * 5) / 100;
        totalReturnedPrice -= reducedPrice;
        break;
    case "20EUROFF":
        totalReturnedPrice -= 20;
        break;
    case "20%OFF":
        var reducedPrice = (totalReturnedPrice * 20) / 100;
        totalReturnedPrice -= reducedPrice;
        break;
    }
});
return totalReturnedPrice;
}