How do you avoid negative quantity in a food ordering app cart?
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 prevents negative quantities and keeps the cart clean.
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More FAQs in Food Ordering App: Common Mistakes in Interviews
Not handling empty cart or no results, allowing negative quantity, incorrect total calculation, spending too much time on CSS, scattered state, not debouncing search, and not testing. Fix each with the appropriate technique.
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). Remember to parseInt the ID and multiply price by quantity.
Yes. Debounce the search input (300ms) to avoid re-rendering the menu on every keystroke. This improves performance, especially with large menus. Use a simple debounce function: clearTimeout + setTimeout.
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