Re: [Json] JSON and int64s - any change in current best practice since I-JSON

Hi,

I had the same thought as Pete a while back, but found that JS engines
actually bar you from encoding these as JSON:

> let two_55th = BigInt(2) ** BigInt(55)
> two_55th
36028797018963968n
> JSON.stringify(two_55th)
VM189:1 Uncaught TypeError: Do not know how to serialize a BigInt
    at JSON.stringify (<anonymous>)
    at <anonymous>:1:6

I can't find the reference for this one, but the reason they gave was that
/adding/ support broke too much running code, even though it would be easy
to add, since the second command there sure does stringify that number.

I think the issue was that too many programs rely on JSON.parse returning a
JavaScript Number type (distinct from BigInt), so you'll run into problems
like this TypeError:

> let my_plain_number = JSON.parse("42")
> my_plain_number
42
> my_plain_number + two_55th
VM429:1 Uncaught TypeError: Cannot mix BigInt and other types, use explicit
conversions
    at <anonymous>:1:17

So, I-JSON remains correct.

thanks,
Rob

On Tue, Jan 16, 2024 at 7:11 AM Tim Bray <tbray@textuality.com> wrote:

> Carsten is right. You probably wouldn’t use JSON if you weren’t likely to
> be interchanging it with other parties over the network, other parties you
> don’t control.  For quite a while, it has been quite likely that the other
> parties use JavaScript, and the limits I-JSON places on numbers are a
> result of this fact. This fact isn’t going away AFAIK.
>
> On Jan 16, 2024 at 6:22:31 AM, Carsten Bormann <cabo@tzi.org> wrote:
>
>> Hi Pete,
>>
>> On 2024-01-16, at 14:46, Pete Cordell <petejson@codalogic.com> wrote:
>>
>>
>> Hi All,
>>
>>
>> In I-JSON it recommends encoding 64-bit values using a string because
>> many parsers (in particular browsers) always represent numbers using
>> floating point doubles.
>>
>>
>> (many parsers == JavaScript’s JSON.parse)
>>
>> We're over 8 years on from I-JSON and browsers now support things like
>> BigInt.
>>
>>
>> I’d say the problem wasn’t so much the absence of BigInt, but the fact
>> that JavaScript’s JSON.parse always parses JSON numbers as a JavaScript
>> Number, which is exact only inside (-2**53, 2**53).
>>
>> Therefore, I'd be interested to hear if there is any community change of
>> opinion on how 64-bit ints should be handled in JSON.
>>
>>
>> I think we’d first need wide support for a new equivalent to JSON.parse
>> in JavaScript.
>>
>> Grüße, Carsten
>>
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>> https://www.ietf.org/mailman/listinfo/json
>>
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