Function getRelativeScrollOffset

modular/sortable.core.esm.js:407–421

* Returns the scroll offset of the given element, added with all the scroll offsets of parent elements. * The value is returned in real pixels. * @param {HTMLElement} el * @return {Array} Offsets in the format of [left, top]

(el)

 * @return {Array}             Offsets in the format of [left, top]
 */
function getRelativeScrollOffset(el) {
  var offsetLeft = 0,
    offsetTop = 0,
    winScroller = getWindowScrollingElement();
  if (el) {
    do {
      var elMatrix = matrix(el),
        scaleX = elMatrix.a,
        scaleY = elMatrix.d;
      offsetLeft += el.scrollLeft * scaleX;
      offsetTop += el.scrollTop * scaleY;
    } while (el !== winScroller && (el = el.parentNode));
  }
  return [offsetLeft, offsetTop];
}

/**
 * Returns the index of the object within the given array