Cart Reducer

CartReducer.jsx

const cartReducer = (state = {
    cartItems: 0,
    items: products,
    cartContents: [],
}, action) => {
    switch (action.type) {
        case "ADD_TO_CART": {
            const existingItem = state.cartContents.find(item => {
                return item.id === Number(action.payload);
            });
            
            let newCart;
            if (existingItem) {
                newCart = state.cartItems.map(item => {
                    if (item.id === Number(action.payload)) {
                        return { ...item, count: item.count + 1}
                    }
                    return item;
                });
            } else {
                newCart = [
                    ...state.cartItems,
                    state.items[action.payload],
                ];
            }
            return {
                ...state,
                cartItems: state.cartItems + 1,
                cartContents: newCart,
            };
            break;
        }

        default:
    }
};