lib/jsdom/living/events/EventTarget-impl.js
function appendToEventPath(eventImpl, target, targetOverride, relatedTarget, touchTargets, slotInClosedTree) {
  const itemInShadowTree = isNode(target) && isShadowRoot(getRoot(target));
  const rootOfClosedTree = isShadowRoot(target) && target.mode === "closed";

  eventImpl._path.push({
    item: target,
    itemInShadowTree,
    target: targetOverride,
    relatedTarget,
    touchTargets,
    rootOfClosedTree,
    slotInClosedTree
  });
}
function appendToEventPath(eventImpl, target, targetOverride, relatedTarget, touchTargets, slotInClosedTree) {
  const itemInShadowTree = isNode(target) && isShadowRoot(getRoot(target));
  const rootOfClosedTree = isShadowRoot(target) && target.mode === "closed";

  eventImpl._path.push({
    item: target,
    itemInShadowTree,
    target: targetOverride,
    relatedTarget,
    touchTargets,
    rootOfClosedTree,
    slotInClosedTree
  });
}
https://dom.spec.whatwg.org/#concept-event-path-append