Function getRootId

src/observe.ts:31–37

* Generate a unique ID for the root element * @param root

(root: IntersectionObserverInit["root"])

 * @param root
 */
function getRootId(root: IntersectionObserverInit["root"]) {
  if (!root) return "0";
  if (RootIds.has(root)) return RootIds.get(root);
  rootId += 1;
  RootIds.set(root, rootId.toString());
  return RootIds.get(root);
}

/**
 * Convert the options to a string Id, based on the values.