I hate this so much because you can’t nicely serialise a BigInt as JSON. Using a...

sheept · 2026-06-06T10:06:18 1780740378

You can serialize a BigInt by specifying a replacer:

    const obj = { a: 9007199254740993n }
    JSON.stringify(obj, (_key, value) => typeof value === 'bigint' ? JSON.rawJSON(value.toString()) : value)

mort96 · 2026-06-06T10:27:23 1780741643

And then you end up with strings on the other side, not numbers.

sheept · 2026-06-06T10:46:42 1780742802

No you don't? The example I gave produces

    {"a":9007199254740993}

not

    {"a":"9007199254740993"}

mort96 · 2026-06-06T14:20:07 1780755607

Oh, that's much worse! The JSON string `{"a":9007199254740993}` decodes to the object `{"a":9007199254740992}` with typical JSON parsers like JavaScript's `JSON.parse`.

sheept · 2026-06-06T18:02:57 1780768977

If you're applying a replacer, then you'd supply a reviver when parsing:

    const json = '{ "a": 9007199254740993 }'
    JSON.parse(json, (_key, value, context) => /^\d+$/.test(context.source) ? BigInt(context.source) : value)

mort96 · 2026-06-06T18:29:37 1780770577

Yeah but now you have the world's biggest foot gun in your API.

marcosdumay · 2026-06-06T17:59:42 1780768782

IMO, I'm tending toward thinking that having types on your readable serialization format is a mistake, and that they should be always input to the (de)serializer instead.

nh2 · 2026-06-06T08:11:26 1780733486

JSON has arbitrary length numbers in the spec only.

mort96 · 2026-06-06T10:26:36 1780741596

Completely and utterly irrelevant.