lib/jsdom/living/helpers/shadow-dom.js
function findSlot(slotable, openFlag) {
  const { parentNode: parent } = slotable;

  if (!parent) {
    return null;
  }

  const shadow = parent._shadowRoot;

  if (!shadow || (openFlag && shadow.mode !== "open")) {
    return null;
  }

  for (const child of domSymbolTree.treeIterator(shadow)) {
    if (isSlot(child) && child.name === slotable._slotableName) {
      return child;
    }
  }

  return null;
}
function findSlot(slotable, openFlag) {
  const { parentNode: parent } = slotable;

  if (!parent) {
    return null;
  }

  const shadow = parent._shadowRoot;

  if (!shadow || (openFlag && shadow.mode !== "open")) {
    return null;
  }

  for (const child of domSymbolTree.treeIterator(shadow)) {
    if (isSlot(child) && child.name === slotable._slotableName) {
      return child;
    }
  }

  return null;
}
function findSlot ( slotable , openFlag ) { const { parentNode : parent } = slotable ; if ( ! parent ) { return null ; } const shadow = parent . _shadowRoot ; if ( ! shadow || ( openFlag && shadow . mode !== "open" ) ) { return null ; } for ( const child of domSymbolTree . treeIterator ( shadow ) ) { if ( isSlot ( child ) && child . name === slotable . _slotableName ) { return child ; } } return null ; }
https://dom.spec.whatwg.org/#find-a-slot
https : // dom . spec . whatwg . org / #find - a - slot