如何在 function 中使用引用嵌套 function 内部参数的条件语句在 javascript 中返回结果？

Question

I have a shopping cart where I need to be able to add a conditional discount to a function that currently gets the price of an item and multiplies it by the quantity. Currently the function works like a charm without the discount however the discount needs to be able to tell if there are two or more items with the same "tag" (ex. "cheese pizza", "mushroom pizza", "Hawaiian pizza") and then subtract an amount from the returned total for it to work. How do I achieve this?

This function gets the total price amount of all items items in the user's cart

 get totalAmount() {
 let total = 0;
 this.cart.forEach(item => (total += this.getItemTotal(item)));

 ///// possible conditional statement here
 ////// something like  if (item.tags == "cheese"){
 /////// return total - 2;   }
 //////// ( currently just errors out to "**item not found**" even though I thought   
 ///// since the parameter "item" was in the function within the function it could recognize it)             


return total;
}

This function is inside the above function. It is used to get an individual item's sub total including it's options

getItemTotal(item) {
 let total = item.price * item.quantity;

  item.options.forEach(option => (total += option.value * item.quantity));
  return total;
  }

Below is an example of an item with a "tag" of cheese. The conditional block needs to determine if there are two tags which are similar like that of cheese and then take away $2 from the total in the first function

     "item": [
     {
     "id": 1,
     "guid": "1d4aa3b2-c059-4fa7-a751-9bca735e4ea1",
     "thumb": "https://foodorderingapp9309.s3-us-west- 
     1.amazonaws.com/CheesySenstions/menu/CheesePizza.JPG",
     "title": "Cheese",
     "body": "try new cheese pizza",
     "tags": ["pizza"],
     }
     ]

Answer 1

You can access the item inside the forEach loop callback.

You can use a counter to count the number of items with a specific tag. Here is an example:

get totalAmount() {
  let total = 0;
  let numberOfItemsWithCheeseTag = 0;

  this.cart.forEach(item => {
    total += this.getItemTotal(item);

    // Increment the counter if 'cheese' is one of the tags
    if (item.tags.includes('cheese')) {
      numberOfItemsWithCheeseTag += 1; // 
    }
  });

  // Apply the discount if the counter reached a threshold
  if (numberOfItemsWithCheeseTag >= 2) {
    total -= 2;
  }        

  return total;
}

Answer 2

Here's a different take

get totalAmount() {
    let total = this.cart.reduce((t, item) => t + this.getItemTotal(item), 0)
    const count = this.cart.reduce((c, item) => c + item.tags.includes('cheese'), 0)

    if (count >= 2) {
        return total -= 2
    }

    return total
}