Even worse, it's not even internally consistent: while the month of the year starts at 0, the day of the month starts at 1. This is one of the worst API design mistakes of Java, and Javascript blindly copied it. At least the newer Java APIs (the java.time ones) fixed that: the month starts at 1 with the newer APIs (when not using the enum). But I don't have much hope of Javascript copying the new and better API.

The reason there's an "exception" for days is that the numbers are the widely-used names for the day of the month. Months arguably don't have widely-used numeric names, although it's pretty reasonably to argue that because numeric month-and-day formatting is so ubiquitous it would have been okay to 1-index the months.

It occurs to me that "9/11" is the one date I can think of where the month is commonly verbally referred to by its number.

That's... a terrible argument.

1970-01-01T00:00:00 is the start of the Unix Epoch, it is definitely not 1970-00-01T00:00:00.

This is consistent across all the warty and various ways to represent the Gregorian calendar, the fifth month is always May, no exceptions.

I think parent means that we often say:

> I get my check on the first of the month

But never really say

> I'm going on vacation for the sixth (month) of the year

Seems like they are just trying to explain the bad decision, not justify it.

Yes, I'm not trying to justify it. And it's not just that we say "the fifth day of May," because it's also true that we can say "the third month." My point is that the fifth day of May is actually named "5" and there's no other name for dates (other than specially=named days, of course).

> Months arguably don't have widely-used numeric names,

You forgot about east asian languages, which all use numeral months.

https://en.wikipedia.org/wiki/Chinese_calendar#Month

https://en.wikipedia.org/wiki/Japanese_calendar#Months

https://en.wikipedia.org/wiki/Korean_calendar#Months

Wasn't the reason for the 0-indexed month that this would make picking the name of the month from the 0-indexed array of month names easier?

That consistent with days of the week, which start at 0 on Sunday.

The bigger WTF is getYear(), which returns the year minus 1,900.

I definitely don't think Brendan "blindly" copied it. At the time, Sun was pushing Java hard. Netscape wanted in on that. So they delivered an edict to "make it look like Java". We can all say, "well I would have pushed back". But it's hard to say what would have happened. He'd have probably been taken off the project.

Hindsight really is 20/20.

>At the time, Sun was pushing Java hard. Netscape wanted in on that. [...] He'd have probably been taken off the project.

Can you elaborate on this? Was netscape owned/funded by Sun?

There was a partnership. The CNet article is still around. https://www.cnet.com/news/netscape-and-sun-unveil-javascript...

It's bizarre that Java....Java....was able to fix this years before JS even really seriously considered it.

I don't know whether JS is fast-evolving or slow-evolving.

That's at least as old as the C language, including also years being since 1900:

https://en.cppreference.com/w/c/chrono/tm

java.util.Date copied it from time.h and Javascript copied it from Java.util.Date.

ISO 8601 has a sensible date format which is an international standard. Gregorian calendar, YYYY-MM-DD, with MM from 01 to 12, and DD from 01 to 31. Days of the week are from 1 to 7, beginning with Monday.

java.util.Date has since been superseded by classes in java.time, which uses ISO 8601.

And also:

    > d.getDay()
    4   // that's the weekday, use getDate()
    > d.getYear()
    120 // that's the year minus 1900, use getFullYear()

This is just one of the many things wrong with the Java Date API:

https://stackoverflow.com/a/1969651/130659

Agreed. This is probably my #1 annoyance.