{
  "object holding itself": (() => {
    const a = { x: 1, inner: { y: 2 } };
    a.self = a;
    a.inner.root = a;
    a.inner.self = a.inner;
    return a;
  })(),
}

--

object holding itself:
{x:1,inner:{y:2,root:<circle>,self:<circle>},self:<circle>}
{
  x: 1,
  inner: {
    y: 2,
    root: <circle>,
    self: <circle>
  },
  self: <circle>
}
{
  x: 1,
  inner: {
    y: 2,
    root: {
      "/circle": 0
    },
    self: {
      "/circle": 1
    }
  },
  self: {
    "/circle": 0
  }
}