const inventory = new Map([
  ["sword", { quantity: 3, weight: 15 }],
  ["shield", { quantity: 1, weight: 25 }],
  ["potion", { quantity: 10, weight: 2 }],
]);

inventory.set("bow", { quantity: 2, weight: 8 });
inventory.delete("shield");

const totalWeight = [...inventory.entries()].reduce((acc, [item, { quantity, weight }]) => {
  return acc + quantity * weight;
}, 0);

const heaviestItem = [...inventory.entries()].reduce((max, [item, data]) =>
  data.weight > max.weight ? { name: item, ...data } : max,
  { name: "", weight: 0 }
);

console.log(inventory.size, totalWeight, heaviestItem.name);