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Comment by kyle-rb | Hacker News Reader

> JavaScript date objects are 1 indexed for years and days, but 0 indexed for months.

I don't disagree that months should be 1-indexed, but I would not make that assumption solely based on days/years being 1-indexed, since 0-indexing those would be psychotic.

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The only reason I can think of to 0-index months is so you can do monthName[date.getMonth()] instead of monthName[date.getMonth() - 1].

I don't think adding counterintuitive behavior to your data to save a "- 1" here and there is a good idea, but I guess this is just legacy from the ancient times.

That would have a better solution in a date.getCurrentMonth(), in my opinion.

Temporal[0] is coming which solves many many many issues with JS Date, 1-based months[1] included!

Can't wait for it to be stable and widely available, it's just too good.

> month values start at 1, which is different from legacy Date where months are represented by zero-based indices (0 to 11)

[0] https://tc39.es/proposal-temporal/docs/

[1] https://tc39.es/proposal-temporal/docs/plaindate.html#month

A [StackOverflow thread](https://stackoverflow.com/a/41992352) about this interface says it was introduced by Java way back in 1995, and copied by the first JavaScript implementation.

(We don't have Markdown formatting here, BTW. But thanks for the heads up, and welcome to YC.)

Why so? Months in written form also start with 1, same as days/years, so it would make sense to match all of them.

For example, the first day of the first month of the first year is 1.1.1 AD (at least for Gregorian calendar), so we could just go with 0-indexed 0.0.0 AD.

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