number counter with animation

const counters = document.querySelectorAll('.counter');
const speed = 400;
counters.forEach(counter => {
  const updateCount = () => {
    const target = +counter.getAttribute('data-counter');
    const count = +counter.innerText.replaceAll(',', '');
    const inc = target / speed;
    if (count < target) {
      counter.innerText = Math.ceil(count + inc).toLocaleString('en-US');
      setTimeout(updateCount, 1);
    } else {
      counter.innerText = target.toLocaleString('en-US');
    }
  };
  const observeElement = function(elements) {
    const element = elements[0];
    if (element.isIntersecting) {
      updateCount();
      observer.unobserve(counter);
    }
  };
  const observer = new IntersectionObserver(observeElement);
  observer.observe(counter);
});