addToCart.js

(() => {
    // all add to cart button
    let allAddToCartButtons = document.querySelectorAll(".addToCartButton");
    let allIncreaseQtyButtons = document.querySelectorAll(".increaseQuantityButton");
    let allDecreaseQtyButtons = document.querySelectorAll(".decreaseQuantityButton");

    // register events on each
    // for add to cart
    for (let addToCartButton of allAddToCartButtons) {
        addToCartButton.addEventListener('click', () => {
            console.log('Clicked', addToCartButton.dataset.price);
        });
    }

    // for increase
    for (let increaseQtyButton of allIncreaseQtyButtons) {
        increaseQtyButton.addEventListener('click', () => {
            let nearbyInput = increaseQtyButton.parentElement.querySelector('input[type=text]');
            let qty = parseInt(nearbyInput.value);
            nearbyInput.value = qty + 1;
        })
    }

    // for decrease
    for (let decreaseQtyButton of allDecreaseQtyButtons) {
        decreaseQtyButton.addEventListener('click', () => {
            let nearbyInput = decreaseQtyButton.parentElement.querySelector('input[type=text]');
            let qty = parseInt(nearbyInput.value);
            nearbyInput.value = (qty !== 0) ? qty - 1 : 0;
        });
    }
})();