[apaprocki]

In TC39, we specified BigInt to not participate in JSON by default, precisely because emitting it as a native JSON number would not be able to be read back by JSON.parse() and many other environments would also not be able to parse it without extra logic if they simply use IEEE754 double.

I explicitly asked for and achieved step 2. in the modified SerializeJSONProperty algorithm[1] so that users could decide and opt-in to serializing BigInts as strings if they so choose, with or without some sigil that could be interpreted by a reviver function. e.g.:

  > JSON.stringify(BigInt(1))
  TypeError: Do not know how to serialize a BigInt
  ...
  > BigInt.prototype.toJSON = function() { return this.toString(); }
  > JSON.stringify(BigInt(1))
  '"1"'

[1]: https://tc39.es/proposal-bigint/#sec-serializejsonproperty