Using IntersectionObserver to detect whether element is in viewport or not

IntersectionObserver.js

const target = document.querySelector('.stickyATCtrigger');
function handleIntersection(entries) {
  entries.map((entry) => {
    if (entry.isIntersecting) {
      // element is in viewport
      $('body').removeClass('sticky-addtocart-mob');
    } else {
      // element is out of viewport
      $('body').addClass('sticky-addtocart-mob');
    }
  });
}
const observer = new IntersectionObserver(handleIntersection);
observer.observe(target);