element fits in viewport html5 code example

Example 1: javascript in viewport

var isInViewport = function (elem) {
    var bounding = elem.getBoundingClientRect();
    return (
        bounding.top >= 0 &&
        bounding.left >= 0 &&
        bounding.bottom <= (window.innerHeight || document.documentElement.clientHeight) &&
        bounding.right <= (window.innerWidth || document.documentElement.clientWidth)
    );
};

Example 2: how to check element is in viewport

function isVisible (ele) {
  const { top, bottom } = ele.getBoundingClientRect();
  const vHeight = (window.innerHeight || document.documentElement.clientHeight);

  return (
    (top > 0 || bottom > 0) &&
    top < vHeight
  );
}