const loadObserver = (handler: () => void) => {
  let waiting = 0;

  return (el: HTMLImageElement) => {
    waiting++;

    const path = el.src;

    el.onload = function () {
      waiting--;

      if (waiting === 0) {
        handler();
      }
    };

    el.onerror = function () {
      waiting--;

      if (waiting === 0) {
        handler();
      }
    };

    el.src = path;
  };
};

export default loadObserver;