Check for html element is visible in viewport by pure javascript (vanilla)

check_elem_is_visible_in_viewport.js

function isVisibleInViewport(id) {
  var element = document.getElementById(id);
  var rect = element.getBoundingClientRect();
  return (
    rect.top >= 0 &&
    rect.left >= 0 &&
    rect.bottom <= (window.innerHeight || document.documentElement.clientHeight) &&
    rect.right <= (window.innerWidth || document.documentElement.clientWidth)
  );
}

//init
console.log(isInViewport("my-element"));
//return true or false