Function isScrolledPast

modular/sortable.core.esm.js:321–339

* Checks if a side of an element is scrolled past a side of its parents * @param {HTMLElement} el The element who's side being scrolled out of view is in question * @param {String} elSide Side of the element in question ('top', 'left', 'right', 'bottom') * @param {String

(el, elSide, parentSide)

 * @return {HTMLElement}               The parent scroll element that the el's side is scrolled past, or null if there is no such element
 */
function isScrolledPast(el, elSide, parentSide) {
  var parent = getParentAutoScrollElement(el, true),
    elSideVal = getRect(el)[elSide];

  /* jshint boss:true */
  while (parent) {
    var parentSideVal = getRect(parent)[parentSide],
      visible = void 0;
    if (parentSide === 'top' || parentSide === 'left') {
      visible = elSideVal >= parentSideVal;
    } else {
      visible = elSideVal <= parentSideVal;
    }
    if (!visible) return parent;
    if (parent === getWindowScrollingElement()) break;
    parent = getParentAutoScrollElement(parent, false);
  }
  return false;
}

/**
 * Gets nth child of el, ignoring hidden children, sortable's elements (does not ignore clone if it's visible)