Relationship between BigInt and Date

[joyeecheung]

I was working on a prototype of BigInt support for fs.Stat in Node.js and I noticed that there are no way to construct a Date out of ms in BigInt. In a conversation with @littledan I learned that it's because Date is Number-based, a better solution for date time with BigInt support would be the Temporal proposal. It would be good if there is explanation in the README about this.

[ljharb]

Is there any reason not to allow a BigInt as well as a Number in Date?

[littledan]

Date's data model is already fundamentally broken. I don't see the point of complicating it with BigInt; precision is sort of the least of Date's problems. I like @maggiepint's approach of a new set of classes to resolve this issue instead.

[ljharb]

I certainly want the Temporal proposal; but I'm not sure making BigInt unergonomic when combined with existing builtins is appropriate.

[littledan]

The BigInt design is predicated on it being OK to be unergonomic in existing libraries and interfaces. We decided it's better to ask programmers to explicitly request the precision loss with a call to Number(). If you want to start improving Date's data model, that sounds like a big project that you could champion.

[apaprocki]

There is a starting-point polyfill for Temporal now, and it uses BigInt. If you'd like to take a peek, please submit feedback there

https://github.com/tc39/proposal-temporal/pull/57/files#diff-4c66be3ac0c3f5b83e963105c61aa60bR39

[littledan]

OK, we'll continue pursuing this effort in the context of the temporal proposal. Thanks everyone! Closing this issue to discuss over there.