MediumJavaScriptPractice mode: untimed, 3 hints

Coupon total

totalWithCoupon(cart, percent) returns the cart total after taking percent% off every item, rounded to 2 decimal places. Callers keep using cart afterwards (to show the original prices), so the function must not change it.

The code has exactly one planted bug. Reproduce it with the tests, fix it with the smallest change, then submit.

Visible tests

cart is left unchanged
- totalWithCoupon([{"name":"pen","price":100,"qty":2}], 10) → 180 · input must not change
no discount
- totalWithCoupon([{"name":"mug","price":250,"qty":1},{"name":"pad","price":40,"qty":3}], 0) → 370

Hints 0/3

// Returns the cart total after taking `percent`% off every item, rounded to 2 decimal places.
// cart: [{ name, price, qty }]. Callers keep using `cart` afterwards (for example to show the
// original prices), so it must not change.
function totalWithCoupon(cart, percent) {
  let total = 0;
  for (const item of cart) {
    item.price = item.price * (1 - percent / 100);
    total += item.price * item.qty;
  }
  return Math.round(total * 100) / 100;
}

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