How do you handle quantity 0 in a cart in JavaScript?
When decrementing, check if the quantity drops to 0 or below. If so, delete the item from the cart: if (cart[id] <= 0) delete cart[id]. This keeps the cart clean and the total accurate.
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More FAQs in Food Ordering App: Cart Implementation in JavaScript
Use an object mapping item ID to quantity: cart = { 1: 2, 3: 1 }. addToCart increments, removeFromCart deletes, changeQuantity adjusts and removes at 0. Calculate total by summing price * qty for each item.
An object with item ID as key and quantity as value: { itemId: quantity }. This gives O(1) lookup, add, and remove. Alternatively, an array of { id, quantity } objects, but the object is simpler for this use case.
Sum price * quantity for each item: Object.entries(cart).reduce((sum, [id, qty]) => { const item = menu.find(m => m.id === parseInt(id)); return sum + item.price * qty; }, 0).
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