Check if an element is in the viewport using getBoundingClientRect method

elementInViewport.js

/**
 * Check if an element is in the viewport using getBoundingClientRect method
 *
 * Copied from: https://www.30secondsofcode.org/js/s/element-is-visible-in-viewport/
 * 
 * @param  object  el               Element object
 * @param  boolean partiallyVisible If element is partially visible or not
 * @return boolean
 */
function elementInViewport(el, partiallyVisible = true) {

  if ( typeof jQuery === "function" && el instanceof jQuery ) {
    el = el.get(0);
  }

  var { top, left, bottom, right } = el.getBoundingClientRect();
  var { innerHeight, innerWidth } = window;

  return partiallyVisible
    ? ((top > 0 && top < innerHeight) ||
        (bottom > 0 && bottom < innerHeight)) &&
        ((left > 0 && left < innerWidth) || (right > 0 && right < innerWidth))
    : top >= 0 && left >= 0 && bottom <= innerHeight && right <= innerWidth;

}