Seat Ledger Closure Walkthrough

The concert desk needs a seat counter that remembers how many reservations have already been accepted. The returned function still has access to remaining after the outer function finishes—that remembered variable is a closure.

function makeSeatDesk(capacity) {
  let remaining = capacity;
  return function reserve() {
    if (remaining === 0) return "Sold out";
    remaining -= 1;
    return `Seats left: ${remaining}`;
  };
}

const eastDesk = makeSeatDesk(2);
const westDesk = makeSeatDesk(1);
console.log(eastDesk());
console.log(westDesk());
console.log(eastDesk());
console.log(eastDesk());

Run it, then predict the final message if eastDesk starts with capacity 3. Each call to the factory creates a separate remaining; calling one desk cannot spend another desk's seats. Build a different stateful tool in the practical lesson.