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// Copyright 2025 Igalia, S.L. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.
/*---
esid: sec-use-of-iana-time-zone-database
description: >
Primary and non-primary time zone identifiers must correspond with IANA Time
Zone Database Zones and Link names, subject to explicit exceptions, and must
direct time zone name canonicalization.
info: |
AvailableNamedTimeZoneIdentifiers ( )
1. Let _identifiers_ be a List containing the String value of each Zone or Link name in the IANA Time Zone Database.
2. ...
3. ...
4. Let _result_ be a new empty List.
5. For each element _identifier_ of _identifiers_, do
a. Let _primary_ be _identifier_.
b. If _identifier_ is a Link name in the IANA Time Zone Database and _identifier_ is not present in the “TZ” column of <code>zone.tab</code> of the IANA Time Zone Database, then
i. Let _zone_ be the Zone name that _identifier_ resolves to, according to the rules for resolving Link names in the IANA Time Zone Database.
ii. If _zone_ starts with *"Etc/"*, then
1. Set _primary_ to _zone_.
iii. Else,
1. Let _identifierCountryCode_ be the <a href="https://www.iso.org/glossary-for-iso-3166.html">ISO 3166-1 Alpha-2</a> country code whose territory contains the geographical area corresponding to _identifier_.
2. Let _zoneCountryCode_ be the ISO 3166-1 Alpha-2 country code whose territory contains the geographical area corresponding to _zone_.
3. If _identifierCountryCode_ is _zoneCountryCode_, then
a. Set _primary_ to _zone_.
4. Else,
a. Let _countryCodeLineCount_ be the number of lines in file <code>zone.tab</code> of the IANA Time Zone Database where the “country-code” column is _identifierCountryCode_.
b. If _countryCodeLineCount_ is 1, then
i. Let _countryCodeLine_ be the line in file <code>zone.tab</code> of the IANA Time Zone Database where the “country-code” column is _identifierCountryCode_.
ii. Set _primary_ to the contents of the “TZ” column of _countryCodeLine_.
c. Else,
i. Let _backzone_ be *undefined*.
ii. Let _backzoneLinkLines_ be the List of lines in the file <code>backzone</code> of the IANA Time Zone Database that start with either *"Link "* or *"#PACKRATLIST zone.tab Link "*.
iii. ...
iv. Assert: _backzone_ is not *undefined*.
v. Set _primary_ to _backzone_.
c. If _primary_ is one of *"Etc/UTC"*, *"Etc/GMT"*, or *"GMT"*, set _primary_ to *"UTC"*.
d. ...
e. Let _record_ be the Time Zone Identifier Record { [[Identifier]]: _identifier_, [[PrimaryIdentifier]]: _primary_ }.
f. Append _record_ to _result_.
6. ...
7. Return _result_.
GetAvailableNamedTimeZoneIdentifier ( _timeZoneIdentifier_ )
1. For each element _record_ of AvailableNamedTimeZoneIdentifiers(), do
a. If _record_.[[Identifier]] is an ASCII-case-insensitive match for _timeZoneIdentifier_, return record.
2. Return ~empty~.
CreateDateTimeFormat ( _newTarget_, _locales_, _options_, _required_, _defaults_ )
29. If IsTimeZoneOffsetString(_timeZone_) is *true*, then
...
30. Else,
a. Let _timeZoneIdentifierRecord_ be GetAvailableNamedTimeZoneIdentifier(_timeZone_).
b. If _timeZoneIdentifierRecord_ is ~empty~, throw a RangeError exception.
c. Set _timeZone_ to _timeZoneIdentifierRecord_.[[PrimaryIdentifier]].
features: [canonical-tz]
---*/
const timeZones = [
// Europe/Prague is not a Link name.
["Europe/Prague", "Europe/Prague"],
// `backward` identifies "Europe/Bratislava" as a Link name targeting "Europe/Prague":
// Link Europe/Prague Europe/Bratislava
// Europe/Bratislava's country code "SK" has only one time zone in `zone.tab`.
["Europe/Bratislava", "Europe/Bratislava"],
// `backward` identifies "Australia/Canberra" as a Link targeting "Australia/Sydney":
// Link Australia/Sydney Australia/Canberra
// Both share the country code "AU".
["Australia/Canberra", "Australia/Sydney"],
// `backward` identifies "Atlantic/Jan_Mayen" as a Link name targeting "Europe/Berlin":
// Link Europe/Berlin Atlantic/Jan_Mayen
// Atlantic/Jan_Mayen's country code "SJ" has only one time zone in `zone.tab`.
["Atlantic/Jan_Mayen", "Arctic/Longyearbyen"],
// `backward` identifies "Pacific/Truk" as a Link name targeting "Pacific/Port_Moresby":
// Link Pacific/Port_Moresby Pacific/Truk #= Pacific/Chuuk
// Pacific/Chuuk's country code "FM" has multiple time zones in `zone.tab`.
// `backzone` identifies "Pacific/Truk" as a Link name targeting "Pacific/Chuuk":
// Link Pacific/Chuuk Pacific/Truk
["Pacific/Truk", "Pacific/Chuuk"],
// `backward` identifies "Etc/UCT" as a Link name targeting "Etc/UTC":
// Link Etc/UTC Etc/UCT
["Etc/UCT", "UTC"],
// `backward` identifies "Etc/GMT0" as a Link name targeting "Etc/GMT":
// Link Etc/GMT Etc/GMT0
["Etc/GMT0", "UTC"]
];
for (const [timeZone, linkTarget] of timeZones) {
assert.sameValue(
new Intl.DateTimeFormat([], { timeZone }).resolvedOptions().timeZone,
timeZone,
"Time zone name " + timeZone + " should be preserved and not canonicalized to " + linkTarget
);
}
reportCompare(0, 0);