Check whether element is in viewport

isInViewPort.js

function isInViewPort(element){
  let elementTop = $(element).offset().top;
  let elementBottom = elementTop + $(element).outerHeight();
  let viewPortTop = $(window).scrollTop();
  let viewPortBottom = viewPortTop + $(window).height();

  return elementBottom > viewPortTop && elementTop < viewPortBottom;
}