orderSummary Component

기존 코드

const getTotal = () => {
    let total = {
      price: 0,
      quantity: 0,
    };

    for (let i = 0; i < cartItems.length; i++) {
      total.quantity = total.quantity + cartItems[i].quantity;
    }

    for (let j = 0; j < renderItems.length; j++) {
      let price = renderItems.filter((el) => el.id === cartItems[j].itemId)[0]
        .price;
      total.price = total.price + price * cartItems[j].quantity;
    }
    return total;
  };

코드 수정

    for (let i = 0; i < cartItems.length; i++) {
      total.quantity = total.quantity + cartItems[i].quantity;
    }

    for (let j = 0; j < cartItems.length; j++) {
      let price = renderItems.filter((el) => el.id === cartItems[j].itemId)[0]
        .price;
      total.price = total.price + price * cartItems[j].quantity;
    }

for문에서 같은 cartItems 배열로 변경 가능

  const getTotal = () => {
    let total = {
      price: 0,
      quantity: 0,
    };

    for (let i = 0; i < cartItems.length; i++) {
      let price = renderItems.filter((el) => el.id === cartItems[i].itemId)[0]
        .price;

      total.quantity = total.quantity + cartItems[i].quantity;
      total.price = total.price + price * cartItems[i].quantity;
    }

    return total;
  };