store.js

 import { proxy } from 'valtio';

const state = proxy({
    cartItems: [],
    userId: "",
    addItem(item) {
        // Check if the item is already in the cart
        const existingItem = this.cartItems.find((cartItem) => cartItem.id === item.id);
        if (existingItem)
        {
            existingItem.count += 1;
        }
        else {
            // If the item is not in the cart, add it as a new item
            this.cartItems.push({ id: item.id, count: 1 });
        }
    },
    removeItem(item) {
        // Find the index of the item in the cart
        const itemIndex = this.cartItems.findIndex((cartItem) => cartItem.id === item.id);

        if (itemIndex !== -1) {
            // If the item is found in the cart, decrease its count
            this.cartItems[itemIndex].count -= 1;

            if (this.cartItems[itemIndex].count === 0) {
                // If the count becomes zero, remove the item from the cart
                this.cartItems.splice(itemIndex, 1);
            }
        }
    },
});

export default state;