// Create a function that will handle any intersection between some elements and the viewport.

const handleHeaderIntersection = function (entries) {

  entries.forEach(entry => {

    if (typeof headerIsVisible === 'function') headerIsNowVisible(entry.isIntersecting);

  });

}

const section_header = document.querySelector("header");

if (section_header) {

  const headerObserver = new IntersectionObserver(handleHeaderIntersection);

  if (headerObserver) headerObserver.observe(section_header);

} else myLog('No header to observe');