Q: How do you implement a cart in a food ordering app 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.

Q: What data structure is best for a shopping cart in JavaScript?

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.

Q: How do you calculate the cart total in a food ordering app?

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).

Question 1

How do you handle quantity 0 in a cart in JavaScript?

Accepted Answer

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.

Question 2

How do you implement a cart in a food ordering app in JavaScript?

Accepted Answer

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.

Question 3

What data structure is best for a shopping cart in JavaScript?

Accepted Answer

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.

Question 4

How do you calculate the cart total in a food ordering app?

Accepted Answer

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).

How do you handle quantity 0 in a cart in JavaScript?

More FAQs in Food Ordering App: Cart Implementation in JavaScript

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