ABlog

function observe(
  callback: (
    mutations: {
      addedNodes: Node[];
      targetNodes: Node[];
      attributeName: string | null;
      attributeNamespace: string | null;
      nextSibling: Node | null;
      oldValue: string | null;
      previousSibling: Node | null;
      removedNodes: Node[];
      target: Node;
      type: MutationRecordType;
    }[],
    observer: MutationObserver
  ) => void,
  target: Node,
  options?: MutationObserverInit
) {
  function getAll(...nodes: Node[]) {
    const tmp = [...nodes];
    for (let i = 0; i < tmp.length; i++) {
      tmp.push(...tmp[i].childNodes);
    }
    return tmp;
  }
  const observer = new MutationObserver((mutationsList) => {
    callback(
      mutationsList.map((mutation) => {
        let _addedNodes: Node[] | null = null;
        let _removedNodes: Node[] | null = null;
        let _targetNodes: Node[] | null = null;
        return {
          type: mutation.type,
          target: mutation.target,
          attributeName: mutation.attributeName,
          attributeNamespace: mutation.attributeNamespace,
          oldValue: mutation.oldValue,
          nextSibling: mutation.nextSibling,
          previousSibling: mutation.previousSibling,
          get addedNodes() {
            _addedNodes ??= getAll(...mutation.addedNodes);
            return _addedNodes;
          },
          get removedNodes() {
            _removedNodes ??= getAll(...mutation.removedNodes);
            return _removedNodes;
          },
          get targetNodes() {
            _targetNodes ??= getAll(mutation.target);
            return _targetNodes;
          },
        };
      }),
      observer
    );
  });
  observer.observe(target, options);
  return observer;
}