epochNanoseconds cannot exceed 10^8 days

[vbackeberg]

I would like to cover dates up until a maximum value of 13 billion years, however "the range of allowed values for this type is the same as the old-style JavaScript Date, 100 million days".

Is there a reason to cap it at 10^8?

As temporal uses bigint, there is no boundary to the size of epochNanoseconds.

[ptomato]

This is a great question, glad you asked it!

There does need to be a cap — we've received a strong signal about this from browser implementors, who would otherwise be concerned about Temporal objects having unbounded storage requirements.

There are a few other concerns about not having a cap:

• beyond a certain point you'd have to make the year field of PlainDate, PlainDateTime, PlainYearMonth, and ZonedDateTime a bigint as well, which would be cumbersome for most normal usage of Temporal.
• the ISO 8601 interchange format requires defining a particular number of digits for the expanded year format (±YYYYYY-MM-DD) that consumers should be able to expect, you are not allowed to emit variable numbers of digits. So beyond a certain point we'd have to decline to serialize some objects and toString() would have to throw instead.

A while back, I wrote a cookbook example of how you might override certain Temporal methods in order to implement Temporal-like objects that supported an arbitrary range of years: https://tc39.es/proposal-temporal/docs/cookbook-expandedyears.html Maybe this approach would be good for your use case? (Although, I suspect you'd probably be better off using a dedicated 3rd-party library instead...)

You can find more discussion on this topic in #24 and #198. I hope that answers your question!

[vbackeberg]

Thanks for your detailed answer!