Function getItemCount

packages/react-stately/src/collections/getItemCount.ts:18–39

(collection: Collection<Node<T>>)

const cache = new WeakMap<Iterable<unknown>, number>();

export function getItemCount<T>(collection: Collection<Node<T>>): number {
  let count = cache.get(collection);
  if (count != null) {
    return count;
  }

  // TS isn't smart enough to know we've ensured count is a number, so use a new variable
  let counter = 0;
  let countItems = (items: Iterable<Node<T>>) => {
    for (let item of items) {
      if (item.type === 'section') {
        countItems(getChildNodes(item, collection));
      } else if (item.type === 'item') {
        counter++;
      }
    }
  };

  countItems(collection);
  cache.set(collection, counter);
  return counter;
}