JSON support for BigInt in Chrome/V8

Michael Theriot michael.lee.theriot at gmail.com
Sat Jul 28 13:56:59 UTC 2018

In a language with arbitrary integer precision, Python 3 for example, the
way to parse a "BigInt" would just be a plain, human readable number
without quotes. The way to serialize it is the same. Any other kind of
representation is out of spec, a workaround, and belongs in userland.

I think BigInt should serialize the same, not as strings or anything that
is not a number. JSON.parse being unable to parse back into BigInt is a
separate issue. It is solvable by using better parsing methods, not the
convenient built-in one which has other issues. E.g. a streaming JSON
parser that lets you inspect the key name and string being parsed can
handle this. Case solved and you can also redesign your code so you are not
creating a temporary object every single parse that you most likely copy
into actual objects later.

Not serializing BigInt is questionable to me but even that can be solved in

On Saturday, July 14, 2018, Anders Rundgren <anders.rundgren.net at gmail.com>

> var small = BigInt("5");
> var big = BigInt("5555555555555555555555555500003");
> JSON.stringify([big,small]);
> VM330:1 Uncaught TypeError: Do not know how to serialize a BigInt
>     at JSON.stringify (<anonymous>)
>     at <anonymous>:1:6
> JSON Number serialization has apparently reached a new level (of
> confusion).
> Personally I don't see the problem.  XML did just fine without hard-coded
> data types.
> The JSON type system is basically a relic from JavaScript.  As such it has
> proved to be quite useful.
> However, when you are outside of that scope, the point with the JSON type
> system gets pretty much zero since you anyway need to map extended types.
> Oracle's JSON-B solution which serializes small values as Number and large
> values as String rather than having a unified serialization based on the
> underlying data type seems like a pretty broken concept although indeed
> fully conforming to the JSON specification. "Like the Devil reads the
> Bible" as we say in Scandinavia :-)
> Adding a couple of double quotes is a major problem?  If so, it seems like
> a way more useful project making quotes optional for keys (named in a
> specific way), like they already are in JavaScript.
> Yeah, and of course adding support for comments.
> Anders
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