I understand how to use Intersection Observer to check if an element has entered the viewport, such as the code below:

const el = document.querySelector('#el')
const observer = new window.IntersectionObserver(([entry]) => {
  if (entry.isIntersecting) {
    console.log('ENTER')
    return
  }
  console.log('LEAVE')
}, {
  root: null,
  threshold: 0.1, // set offset 0.1 means trigger if atleast 10% of element in viewport
})

observer.observe(el);

Is it possible to detect if the element crossed the middle of the viewport('50vh' from the top)?

If so, could you please include a code example for clarity?