Function findCommonOffsetParent

app/src/static/js/react-bootstrap.js:3233–3265

* Finds the offset parent common to the two provided nodes * @method * @memberof Popper.Utils * @argument {Element} element1 * @argument {Element} element2 * @returns {Element} common offset parent

(element1, element2)

function findCommonOffsetParent(element1, element2) {
  // This check is needed to avoid errors in case one of the elements isn't defined for any reason
  if (!element1 || !element1.nodeType || !element2 || !element2.nodeType) {
    return document.documentElement;
  } // Here we make sure to give as "start" the element that comes first in the DOM


  var order = element1.compareDocumentPosition(element2) & Node.DOCUMENT_POSITION_FOLLOWING;
  var start = order ? element1 : element2;
  var end = order ? element2 : element1; // Get common ancestor container

  var range = document.createRange();
  range.setStart(start, 0);
  range.setEnd(end, 0);
  var commonAncestorContainer = range.commonAncestorContainer; // Both nodes are inside #document

  if (element1 !== commonAncestorContainer && element2 !== commonAncestorContainer || start.contains(end)) {
    if (isOffsetContainer(commonAncestorContainer)) {
      return commonAncestorContainer;
    }

    return getOffsetParent(commonAncestorContainer);
  } // one of the nodes is inside shadowDOM, find which one


  var element1root = getRoot(element1);

  if (element1root.host) {
    return findCommonOffsetParent(element1root.host, element2);
  } else {
    return findCommonOffsetParent(element1, getRoot(element2).host);
  }
}
/**
 * Gets the scroll value of the given element in the given side (top and left)
 * @method