Merhabalar. HTML ile bir site yazıyorum. Javascript kodumda bir hata var ama çözemedim. Bu konuda profesyonel olan arkadaşlar yardımcı olabilirler mi?

Problem şu; fiyat azaltma butonuna bastığımda fiyat arttırma butonuyla aynı işi yapıyor. Yani fiyatı arttırıyor. Bunu nasıl düzeltebilirim?

document.addEventListener('DOMContentLoaded', function() {
    const decreaseBtns = document.querySelectorAll('.decrease-btn');
    const increaseBtns = document.querySelectorAll('.increase-btn');
    const quantityValues = document.querySelectorAll('.item-quantity');
    const deleteIcons = document.querySelectorAll('.delete-icon');
    const items = document.querySelectorAll('.item');
    const itemPrices = document.querySelectorAll('.item-price');
    const checkoutBtn = document.querySelector('.payment-btn');
    const totalPriceElement = document.getElementById('total-price');
    const cartItemsContainer = document.querySelector('.cart-items');
    
    // Total price'i güncelle
    updateTotalPrice();

    checkoutBtn.addEventListener('click', function() {
        window.location.href = 'payment.html';
    });

    function performSearch() {
        var searchValue = document.getElementById('search-input').value;
        alert('You searched for: ' + searchValue);
    }

    document.getElementById('search-icon').addEventListener('click', performSearch);
    document.getElementById('search-input').addEventListener('keydown', function (event) {
        if (event.key === 'Enter') {
            event.preventDefault();
            performSearch();
        }
    });

    decreaseBtns.forEach(function(btn, index) {
        btn.addEventListener('click', function() {
            let currentValue = parseInt(quantityValues[index].textContent);
            if (currentValue > 1) {
                quantityValues[index].textContent = currentValue - 1;
                updateTotalPrice();
                updateCartDropdown();
            }
        });
    });

    increaseBtns.forEach(function(btn, index) {
        btn.addEventListener('click', function() {
            let currentValue = parseInt(quantityValues[index].textContent);
            quantityValues[index].textContent = currentValue + 1;
            updateTotalPrice();
            updateCartDropdown();
        });
    });

    deleteIcons.forEach(function(icon, index) {
        icon.addEventListener('click', function() {
            items[index].remove();
            updateTotalPrice();
            updateCartDropdown();
        });
    });

    function updateTotalPrice() {
        let totalPrice = 0;
        items.forEach((item, index) => {
            if (item.parentElement) {
                let quantity = parseInt(quantityValues[index].textContent);
                let pricePerItem = parseFloat(itemPrices[index].textContent);
                let itemTotal = quantity * pricePerItem;
                totalPrice += itemTotal;
                itemPrices[index].textContent = itemTotal.toFixed(2) + ' TL';
            }
        });
        totalPriceElement.textContent = totalPrice.toFixed(2);
    }

    function updateCartDropdown() {
        cartItemsContainer.innerHTML = '';
        items.forEach((item, index) => {
            if (item.parentElement) {
                let itemName = item.querySelector('.item-details h3').textContent;
                let itemPrice = item.querySelector('.item-price').textContent;
                let itemImageSrc = item.querySelector('.item-info img').src;
                let quantity = parseInt(quantityValues[index].textContent);
                let itemHTML = `
                    <div class="cart-item">
                        <img src="${itemImageSrc}" alt="${itemName}">
                        <div>
                            <span>${itemName}</span>
                            <span>Price: ${itemPrice}</span>
                            <span>Quantity: ${quantity}</span>
                        </div>
                    </div>
            `   ;
                cartItemsContainer.innerHTML += itemHTML;
            }
        });
    }

    document.querySelector('.checkout-button').addEventListener('click', function () {
        window.location.href = 'checkout.html';
    });

    document.querySelector('.continue-shopping-button').addEventListener('click', function () {
        window.location.href = 'cart.html';
    });

    // Initialize cart dropdown on page load
    updateCartDropdown();
});