30-seconds-of-code/snippets/js/s/stringify-circular-json.md

title, type, language, tags, cover, dateModified

title	type	language	tags	cover	dateModified
Stringify circular JSON	snippet	javascript	object	waving-over-lake	2020-10-22T20:24:30+03:00

Serializes a JSON object containing circular references into a JSON format.

• Create a WeakSet to store and check seen values, using WeakSet.prototype.add() and WeakSet.prototype.has().
• Use JSON.stringify() with a custom replacer function that omits values already in seen, adding new values as necessary.
• ⚠️ NOTICE: This function finds and removes circular references, which causes circular data loss in the serialized JSON.

const stringifyCircularJSON = obj => {
  const seen = new WeakSet();
  return JSON.stringify(obj, (k, v) => {
    if (v !== null && typeof v === 'object') {
      if (seen.has(v)) return;
      seen.add(v);
    }
    return v;
  });
};

const obj = { n: 42 };
obj.obj = obj;
stringifyCircularJSON(obj); // '{"n": 42}'