Other engines don't give NaN if there is at least one digit after the
dot for milliseconds. We were much stricter and required exactly three
digits.
But there is real world usage of different amounts of digits such as
discord having three extra trailing zeros.
This is a normative change in the ECMA-262 spec:
ca53334
Note that this also fixes a few errors where we errantly converted the
stored time value to local time.
Mostly slapping "timeZone: UTC" on DateTimeFormat tests (we have other
tests for specific time zones). Also pick dates that are not on DST
boundaries in some time zones where that matters.
First, this adds a constructor to the Date object to be created from a
plain double. This is a first step to removing Core::DateTime as the
basis for the Date object. A subsequent commit will remove the now-
unused data from the object.
Next, this implements the constructor in accordance to the spec. The
constructor when NewTarget is undefined no longer allocates a Date on
the heap. The other constructor properly uses recently created AOs to
handle time zone and ensure the created [[DateValue]] is valid. Other
methods on the constructor (Date.now) have not been touched yet.
Last, the prototype is reimplemented. Again, we use other AOs to handle
time zones and time clipping. Not all prototypes are fixed; most of them
are, but a few (e.g. Date.prototype.getTimezoneOffset) were not fixed,
but left in a mostly unimplemented state for another commit.
In all of the above, spec comments are added. This is a rather large
change; but it's tough to do any of these parts individually without
breaking everything else.
This fixes all failing Date.UTC test262 tests, which failed due to not
handling invalid input and evaluating inputs out of order. But this also
avoids using timegm(), which doesn't work on macOS for years before 1900
(they simply return -1 for those years).
Partially addresses #4651. Date.parse.js still fails.
Currently, we have NotA and NotAn, to be used dependent on whether the
following word begins with a vowel or not. To avoid this, change the
wording on NotA to be independent of this context.
...for the non-success state. This fixes a crash when parsing dates with
the year -1, as we would assert successful parsing ("year != -1").
Mixing Optional and -1 seems worse and more complicated than just using
Optional for all the values, so I did that instead.
It is defined as follows:
21.4.3.1 Date.now ( )
https://tc39.es/ecma262/#sec-date.now
The now function returns the time value designating the UTC date and
time of the occurrence of the call to now.
"Time value" is defined as:
21.4.1.1 Time Values and Time Range
https://tc39.es/ecma262/#sec-time-values-and-time-range
An ECMAScript time value is a Number, either a finite integral
Number representing an instant in time to millisecond precision or
NaN representing no specific instant.
By flooring the value we match the behavior in the Temporal proposal's
Temporal.ZonedDateTime.prototype.epochMilliseconds getter:
4. Let ms be RoundTowardsZero(ℝ(ns) / 10^6).
With that being defined as:
13.30 RoundTowardsZero ( x )
https://tc39.es/proposal-temporal/#sec-temporal-roundtowardszero
1. Return the mathematical value that is the same sign as x and
whose magnitude is floor(abs(x)).
This is makes the last of the currently 15 Temporal tests in test262
work, which compares Temporal.now.instant() with Date.now() :^)
Since DateTime stores months as 1 to 12, while JS accepts months as
0 to 11, we have to account for the difference (by subtracting or
adding 1) where appropriate.
