這是什麼?

{ options:
   { withDomLvl1: true,
     normalizeWhitespace: false,
     xmlMode: false,
     decodeEntities: true },
  _root:
   { '0':
      { type: 'root',
        name: 'root',
        attribs: {},
        children: [Object],
        next: null,
        prev: null,
        parent: null },
     options:
      { withDomLvl1: true,
        normalizeWhitespace: false,
        xmlMode: false,
        decodeEntities: true },
     length: 1,
     _root: [Circular] },
  length: 0,
  prevObject:
   { '0':
      { type: 'root',
        name: 'root',
        attribs: {},
        children: [Object],
        next: null,
        prev: null,
        parent: null },
     options:
      { withDomLvl1: true,
        normalizeWhitespace: false,
        xmlMode: false,
        decodeEntities: true },
     length: 1,
     _root: [Circular] } }