const ratio = 0.5;
const options = {
  root: null,
  rootMargin: '0px',
  threshold: ratio
}
const callback = function (entries, observer) {
  entries.forEach(entry => {
    console.log(entry.intersectionRatio)
    if (entry.intersectionRatio > ratio) {
      document.querySelector('.revealForm').classList.add('show')
      observer.unobserve(entry.target);
    } 
  });
}

console.log(options.threshold)

let observer = new IntersectionObserver(callback, options)
observer.observe(document.querySelector('.revealForm'))