{
  "array holding itself": (() => {
    const a = [1, 2];
    a.push(a);
    return a;
  })(),
}

--

array holding itself:
[1,2,<circle>]
[
  1,
  2,
  <circle>
]
[
  1,
  2,
  {
    "/circle": 0
  }
]