How to get a list of all supported timezones? - node.js

Question

How can we get a list of all supported timezones in NodeJs at runtime?
use-cases:
we want to implement a check when the application starts to make sure that the main timezone (set via env-var) is correct).
we want to show a list to the user so that they can select only valid time-zones
The nodejs docs mention that node can be used with different ICU settings, so a hardcoded list (like timezones.json) will not work.
I found some related questions, but none seems to answer this (simple?) question...
e.g. Where does Node.js get the Timezone data from?

Answer 1

I think that currently there is no easy way to get the list of supported timezones in node.js at runtime:
JavaScript Internationalization Api:
The specification does not provide a way to get the list of supported timezones
NodeJs:
NodeJs also does not provide a way go get the list of supported timezones
Workaround
A workaround is to somehow get a list of timezones and test each one separately.
There are many predefined timezone lists:
IANA Timezone database
Wikipedia: List of tz database time zones
Json Timezone List
Csv Timezone List
However, since we have a database application, we first get the list of all timezones supported by the database - see PostgreSql docs:
SELECT name
FROM pg_timezone_names
ORDER BY name;
and then check for each one if it is supported by nodejs (here's some typescript pseudo code):
try {
new Intl.DateTimeFormat('en-US', {
timeZone
})
// timezone is valid - add to the valid list
} catch (e) {
// timezone is invalid - maybe write a log msg
}
Stackblitz Test
Now we have a list of all timezones that are valid in the database and in NodeJs.
There are currently (PostgreSql 12, NodeJs 14):
547 valid timezones
49 invalid timezones (i.e. known by PostgreSql, but not by NodeJs): e.g. America/Argentina/ComodRivadavia, US/Alaska, ..

Answer 2

If you need a detailed JSON file, check out https://github.com/dmfilipenko/timezones.json/blob/master/timezones.json.
However, if you just need the names (e.g. America/Los_Angeles) in a JSON array, the following 3-liner script in Node.js would work to get that from timezones.json.
const namesSet = new Set();
require("timezones.json").forEach((tzDefinition) => tzDefinition.utc.forEach((tzName) => namesSet.add(tzName)));
console.log(JSON.stringify([...namesSet].sort()));
Output on 2021/11/14 from "timezones.json": "1.5.3":
["Africa/Abidjan","Africa/Accra","Africa/Addis_Ababa","Africa/Algiers","Africa/Asmera","Africa/Bamako","Africa/Bangui","Africa/Banjul","Africa/Bissau","Africa/Blantyre","Africa/Brazzaville","Africa/Bujumbura","Africa/Cairo","Africa/Casablanca","Africa/Ceuta","Africa/Conakry","Africa/Dakar","Africa/Dar_es_Salaam","Africa/Djibouti","Africa/Douala","Africa/El_Aaiun","Africa/Freetown","Africa/Gaborone","Africa/Harare","Africa/Johannesburg","Africa/Juba","Africa/Kampala","Africa/Khartoum","Africa/Kigali","Africa/Kinshasa","Africa/Lagos","Africa/Libreville","Africa/Lome","Africa/Luanda","Africa/Lubumbashi","Africa/Lusaka","Africa/Malabo","Africa/Maputo","Africa/Maseru","Africa/Mbabane","Africa/Mogadishu","Africa/Monrovia","Africa/Nairobi","Africa/Ndjamena","Africa/Niamey","Africa/Nouakchott","Africa/Ouagadougou","Africa/Porto-Novo","Africa/Sao_Tome","Africa/Tripoli","Africa/Tunis","Africa/Windhoek","America/Anchorage","America/Anguilla","America/Antigua","America/Araguaina","America/Argentina/La_Rioja","America/Argentina/Rio_Gallegos","America/Argentina/Salta","America/Argentina/San_Juan","America/Argentina/San_Luis","America/Argentina/Tucuman","America/Argentina/Ushuaia","America/Aruba","America/Asuncion","America/Bahia","America/Bahia_Banderas","America/Barbados","America/Belem","America/Belize","America/Blanc-Sablon","America/Boa_Vista","America/Bogota","America/Boise","America/Buenos_Aires","America/Cambridge_Bay","America/Campo_Grande","America/Cancun","America/Caracas","America/Catamarca","America/Cayenne","America/Cayman","America/Chicago","America/Chihuahua","America/Coral_Harbour","America/Cordoba","America/Costa_Rica","America/Creston","America/Cuiaba","America/Curacao","America/Danmarkshavn","America/Dawson","America/Dawson_Creek","America/Denver","America/Detroit","America/Dominica","America/Edmonton","America/Eirunepe","America/El_Salvador","America/Fortaleza","America/Glace_Bay","America/Godthab","America/Goose_Bay","America/Grand_Turk","America/Grenada","America/Guadeloupe","America/Guatemala","America/Guayaquil","America/Guyana","America/Halifax","America/Havana","America/Hermosillo","America/Indiana/Knox","America/Indiana/Marengo","America/Indiana/Petersburg","America/Indiana/Tell_City","America/Indiana/Vevay","America/Indiana/Vincennes","America/Indiana/Winamac","America/Indianapolis","America/Inuvik","America/Iqaluit","America/Jamaica","America/Jujuy","America/Juneau","America/Kentucky/Monticello","America/Kralendijk","America/La_Paz","America/Lima","America/Los_Angeles","America/Louisville","America/Lower_Princes","America/Maceio","America/Managua","America/Manaus","America/Marigot","America/Martinique","America/Matamoros","America/Mazatlan","America/Mendoza","America/Menominee","America/Merida","America/Mexico_City","America/Moncton","America/Monterrey","America/Montevideo","America/Montreal","America/Montserrat","America/Nassau","America/New_York","America/Nipigon","America/Nome","America/Noronha","America/North_Dakota/Beulah","America/North_Dakota/Center","America/North_Dakota/New_Salem","America/Ojinaga","America/Panama","America/Pangnirtung","America/Paramaribo","America/Phoenix","America/Port-au-Prince","America/Port_of_Spain","America/Porto_Velho","America/Puerto_Rico","America/Rainy_River","America/Rankin_Inlet","America/Recife","America/Regina","America/Resolute","America/Rio_Branco","America/Santa_Isabel","America/Santarem","America/Santiago","America/Santo_Domingo","America/Sao_Paulo","America/Scoresbysund","America/Sitka","America/St_Barthelemy","America/St_Johns","America/St_Kitts","America/St_Lucia","America/St_Thomas","America/St_Vincent","America/Swift_Current","America/Tegucigalpa","America/Thule","America/Thunder_Bay","America/Tijuana","America/Toronto","America/Tortola","America/Vancouver","America/Whitehorse","America/Winnipeg","America/Yakutat","America/Yellowknife","Antarctica/Casey","Antarctica/Davis","Antarctica/DumontDUrville","Antarctica/Macquarie","Antarctica/Mawson","Antarctica/McMurdo","Antarctica/Palmer","Antarctica/Rothera","Antarctica/Syowa","Antarctica/Vostok","Arctic/Longyearbyen","Asia/Aden","Asia/Almaty","Asia/Amman","Asia/Anadyr","Asia/Aqtau","Asia/Aqtobe","Asia/Ashgabat","Asia/Baghdad","Asia/Bahrain","Asia/Baku","Asia/Bangkok","Asia/Beirut","Asia/Bishkek","Asia/Brunei","Asia/Calcutta","Asia/Chita","Asia/Choibalsan","Asia/Colombo","Asia/Damascus","Asia/Dhaka","Asia/Dili","Asia/Dubai","Asia/Dushanbe","Asia/Hong_Kong","Asia/Hovd","Asia/Irkutsk","Asia/Jakarta","Asia/Jayapura","Asia/Jerusalem","Asia/Kabul","Asia/Kamchatka","Asia/Karachi","Asia/Kathmandu","Asia/Khandyga","Asia/Kolkata","Asia/Krasnoyarsk","Asia/Kuala_Lumpur","Asia/Kuching","Asia/Kuwait","Asia/Macau","Asia/Magadan","Asia/Makassar","Asia/Manila","Asia/Muscat","Asia/Nicosia","Asia/Novokuznetsk","Asia/Novosibirsk","Asia/Omsk","Asia/Oral","Asia/Phnom_Penh","Asia/Pontianak","Asia/Pyongyang","Asia/Qatar","Asia/Qyzylorda","Asia/Rangoon","Asia/Riyadh","Asia/Saigon","Asia/Sakhalin","Asia/Samarkand","Asia/Seoul","Asia/Shanghai","Asia/Singapore","Asia/Srednekolymsk","Asia/Taipei","Asia/Tashkent","Asia/Tbilisi","Asia/Tehran","Asia/Thimphu","Asia/Tokyo","Asia/Ulaanbaatar","Asia/Urumqi","Asia/Ust-Nera","Asia/Vientiane","Asia/Vladivostok","Asia/Yakutsk","Asia/Yekaterinburg","Asia/Yerevan","Atlantic/Azores","Atlantic/Bermuda","Atlantic/Canary","Atlantic/Cape_Verde","Atlantic/Faeroe","Atlantic/Madeira","Atlantic/Reykjavik","Atlantic/South_Georgia","Atlantic/St_Helena","Atlantic/Stanley","Australia/Adelaide","Australia/Brisbane","Australia/Broken_Hill","Australia/Currie","Australia/Darwin","Australia/Hobart","Australia/Lindeman","Australia/Melbourne","Australia/Perth","Australia/Sydney","CST6CDT","EST5EDT","Etc/GMT","Etc/GMT+1","Etc/GMT+10","Etc/GMT+11","Etc/GMT+12","Etc/GMT+2","Etc/GMT+3","Etc/GMT+4","Etc/GMT+5","Etc/GMT+6","Etc/GMT+7","Etc/GMT-1","Etc/GMT-10","Etc/GMT-11","Etc/GMT-12","Etc/GMT-13","Etc/GMT-2","Etc/GMT-3","Etc/GMT-4","Etc/GMT-5","Etc/GMT-6","Etc/GMT-7","Etc/GMT-8","Etc/GMT-9","Europe/Amsterdam","Europe/Andorra","Europe/Astrakhan","Europe/Athens","Europe/Belgrade","Europe/Berlin","Europe/Bratislava","Europe/Brussels","Europe/Bucharest","Europe/Budapest","Europe/Busingen","Europe/Chisinau","Europe/Copenhagen","Europe/Dublin","Europe/Gibraltar","Europe/Guernsey","Europe/Helsinki","Europe/Isle_of_Man","Europe/Istanbul","Europe/Jersey","Europe/Kaliningrad","Europe/Kiev","Europe/Kirov","Europe/Lisbon","Europe/Ljubljana","Europe/London","Europe/Luxembourg","Europe/Madrid","Europe/Malta","Europe/Mariehamn","Europe/Minsk","Europe/Monaco","Europe/Moscow","Europe/Nicosia","Europe/Oslo","Europe/Paris","Europe/Podgorica","Europe/Prague","Europe/Riga","Europe/Rome","Europe/Samara","Europe/San_Marino","Europe/Sarajevo","Europe/Simferopol","Europe/Skopje","Europe/Sofia","Europe/Stockholm","Europe/Tallinn","Europe/Tirane","Europe/Ulyanovsk","Europe/Uzhgorod","Europe/Vaduz","Europe/Vatican","Europe/Vienna","Europe/Vilnius","Europe/Volgograd","Europe/Warsaw","Europe/Zagreb","Europe/Zaporozhye","Europe/Zurich","Indian/Antananarivo","Indian/Chagos","Indian/Christmas","Indian/Cocos","Indian/Comoro","Indian/Kerguelen","Indian/Mahe","Indian/Maldives","Indian/Mauritius","Indian/Mayotte","Indian/Reunion","MST7MDT","PST8PDT","Pacific/Apia","Pacific/Auckland","Pacific/Efate","Pacific/Enderbury","Pacific/Fakaofo","Pacific/Fiji","Pacific/Funafuti","Pacific/Galapagos","Pacific/Guadalcanal","Pacific/Guam","Pacific/Honolulu","Pacific/Johnston","Pacific/Kosrae","Pacific/Kwajalein","Pacific/Majuro","Pacific/Midway","Pacific/Nauru","Pacific/Niue","Pacific/Noumea","Pacific/Pago_Pago","Pacific/Palau","Pacific/Ponape","Pacific/Port_Moresby","Pacific/Rarotonga","Pacific/Saipan","Pacific/Tahiti","Pacific/Tarawa","Pacific/Tongatapu","Pacific/Truk","Pacific/Wake","Pacific/Wallis"]
Pretty-printed:
// 434 entries extracted from "timezones.json#1.5.3" package at 2021-11-14T20:03:29.078Z
[
"Africa/Abidjan",
"Africa/Accra",
"Africa/Addis_Ababa",
"Africa/Algiers",
"Africa/Asmera",
"Africa/Bamako",
"Africa/Bangui",
"Africa/Banjul",
"Africa/Bissau",
"Africa/Blantyre",
"Africa/Brazzaville",
"Africa/Bujumbura",
"Africa/Cairo",
"Africa/Casablanca",
"Africa/Ceuta",
"Africa/Conakry",
"Africa/Dakar",
"Africa/Dar_es_Salaam",
"Africa/Djibouti",
"Africa/Douala",
"Africa/El_Aaiun",
"Africa/Freetown",
"Africa/Gaborone",
"Africa/Harare",
"Africa/Johannesburg",
"Africa/Juba",
"Africa/Kampala",
"Africa/Khartoum",
"Africa/Kigali",
"Africa/Kinshasa",
"Africa/Lagos",
"Africa/Libreville",
"Africa/Lome",
"Africa/Luanda",
"Africa/Lubumbashi",
"Africa/Lusaka",
"Africa/Malabo",
"Africa/Maputo",
"Africa/Maseru",
"Africa/Mbabane",
"Africa/Mogadishu",
"Africa/Monrovia",
"Africa/Nairobi",
"Africa/Ndjamena",
"Africa/Niamey",
"Africa/Nouakchott",
"Africa/Ouagadougou",
"Africa/Porto-Novo",
"Africa/Sao_Tome",
"Africa/Tripoli",
"Africa/Tunis",
"Africa/Windhoek",
"America/Anchorage",
"America/Anguilla",
"America/Antigua",
"America/Araguaina",
"America/Argentina/La_Rioja",
"America/Argentina/Rio_Gallegos",
"America/Argentina/Salta",
"America/Argentina/San_Juan",
"America/Argentina/San_Luis",
"America/Argentina/Tucuman",
"America/Argentina/Ushuaia",
"America/Aruba",
"America/Asuncion",
"America/Bahia",
"America/Bahia_Banderas",
"America/Barbados",
"America/Belem",
"America/Belize",
"America/Blanc-Sablon",
"America/Boa_Vista",
"America/Bogota",
"America/Boise",
"America/Buenos_Aires",
"America/Cambridge_Bay",
"America/Campo_Grande",
"America/Cancun",
"America/Caracas",
"America/Catamarca",
"America/Cayenne",
"America/Cayman",
"America/Chicago",
"America/Chihuahua",
"America/Coral_Harbour",
"America/Cordoba",
"America/Costa_Rica",
"America/Creston",
"America/Cuiaba",
"America/Curacao",
"America/Danmarkshavn",
"America/Dawson",
"America/Dawson_Creek",
"America/Denver",
"America/Detroit",
"America/Dominica",
"America/Edmonton",
"America/Eirunepe",
"America/El_Salvador",
"America/Fortaleza",
"America/Glace_Bay",
"America/Godthab",
"America/Goose_Bay",
"America/Grand_Turk",
"America/Grenada",
"America/Guadeloupe",
"America/Guatemala",
"America/Guayaquil",
"America/Guyana",
"America/Halifax",
"America/Havana",
"America/Hermosillo",
"America/Indiana/Knox",
"America/Indiana/Marengo",
"America/Indiana/Petersburg",
"America/Indiana/Tell_City",
"America/Indiana/Vevay",
"America/Indiana/Vincennes",
"America/Indiana/Winamac",
"America/Indianapolis",
"America/Inuvik",
"America/Iqaluit",
"America/Jamaica",
"America/Jujuy",
"America/Juneau",
"America/Kentucky/Monticello",
"America/Kralendijk",
"America/La_Paz",
"America/Lima",
"America/Los_Angeles",
"America/Louisville",
"America/Lower_Princes",
"America/Maceio",
"America/Managua",
"America/Manaus",
"America/Marigot",
"America/Martinique",
"America/Matamoros",
"America/Mazatlan",
"America/Mendoza",
"America/Menominee",
"America/Merida",
"America/Mexico_City",
"America/Moncton",
"America/Monterrey",
"America/Montevideo",
"America/Montreal",
"America/Montserrat",
"America/Nassau",
"America/New_York",
"America/Nipigon",
"America/Nome",
"America/Noronha",
"America/North_Dakota/Beulah",
"America/North_Dakota/Center",
"America/North_Dakota/New_Salem",
"America/Ojinaga",
"America/Panama",
"America/Pangnirtung",
"America/Paramaribo",
"America/Phoenix",
"America/Port-au-Prince",
"America/Port_of_Spain",
"America/Porto_Velho",
"America/Puerto_Rico",
"America/Rainy_River",
"America/Rankin_Inlet",
"America/Recife",
"America/Regina",
"America/Resolute",
"America/Rio_Branco",
"America/Santa_Isabel",
"America/Santarem",
"America/Santiago",
"America/Santo_Domingo",
"America/Sao_Paulo",
"America/Scoresbysund",
"America/Sitka",
"America/St_Barthelemy",
"America/St_Johns",
"America/St_Kitts",
"America/St_Lucia",
"America/St_Thomas",
"America/St_Vincent",
"America/Swift_Current",
"America/Tegucigalpa",
"America/Thule",
"America/Thunder_Bay",
"America/Tijuana",
"America/Toronto",
"America/Tortola",
"America/Vancouver",
"America/Whitehorse",
"America/Winnipeg",
"America/Yakutat",
"America/Yellowknife",
"Antarctica/Casey",
"Antarctica/Davis",
"Antarctica/DumontDUrville",
"Antarctica/Macquarie",
"Antarctica/Mawson",
"Antarctica/McMurdo",
"Antarctica/Palmer",
"Antarctica/Rothera",
"Antarctica/Syowa",
"Antarctica/Vostok",
"Arctic/Longyearbyen",
"Asia/Aden",
"Asia/Almaty",
"Asia/Amman",
"Asia/Anadyr",
"Asia/Aqtau",
"Asia/Aqtobe",
"Asia/Ashgabat",
"Asia/Baghdad",
"Asia/Bahrain",
"Asia/Baku",
"Asia/Bangkok",
"Asia/Beirut",
"Asia/Bishkek",
"Asia/Brunei",
"Asia/Calcutta",
"Asia/Chita",
"Asia/Choibalsan",
"Asia/Colombo",
"Asia/Damascus",
"Asia/Dhaka",
"Asia/Dili",
"Asia/Dubai",
"Asia/Dushanbe",
"Asia/Hong_Kong",
"Asia/Hovd",
"Asia/Irkutsk",
"Asia/Jakarta",
"Asia/Jayapura",
"Asia/Jerusalem",
"Asia/Kabul",
"Asia/Kamchatka",
"Asia/Karachi",
"Asia/Kathmandu",
"Asia/Khandyga",
"Asia/Kolkata",
"Asia/Krasnoyarsk",
"Asia/Kuala_Lumpur",
"Asia/Kuching",
"Asia/Kuwait",
"Asia/Macau",
"Asia/Magadan",
"Asia/Makassar",
"Asia/Manila",
"Asia/Muscat",
"Asia/Nicosia",
"Asia/Novokuznetsk",
"Asia/Novosibirsk",
"Asia/Omsk",
"Asia/Oral",
"Asia/Phnom_Penh",
"Asia/Pontianak",
"Asia/Pyongyang",
"Asia/Qatar",
"Asia/Qyzylorda",
"Asia/Rangoon",
"Asia/Riyadh",
"Asia/Saigon",
"Asia/Sakhalin",
"Asia/Samarkand",
"Asia/Seoul",
"Asia/Shanghai",
"Asia/Singapore",
"Asia/Srednekolymsk",
"Asia/Taipei",
"Asia/Tashkent",
"Asia/Tbilisi",
"Asia/Tehran",
"Asia/Thimphu",
"Asia/Tokyo",
"Asia/Ulaanbaatar",
"Asia/Urumqi",
"Asia/Ust-Nera",
"Asia/Vientiane",
"Asia/Vladivostok",
"Asia/Yakutsk",
"Asia/Yekaterinburg",
"Asia/Yerevan",
"Atlantic/Azores",
"Atlantic/Bermuda",
"Atlantic/Canary",
"Atlantic/Cape_Verde",
"Atlantic/Faeroe",
"Atlantic/Madeira",
"Atlantic/Reykjavik",
"Atlantic/South_Georgia",
"Atlantic/St_Helena",
"Atlantic/Stanley",
"Australia/Adelaide",
"Australia/Brisbane",
"Australia/Broken_Hill",
"Australia/Currie",
"Australia/Darwin",
"Australia/Hobart",
"Australia/Lindeman",
"Australia/Melbourne",
"Australia/Perth",
"Australia/Sydney",
"CST6CDT",
"EST5EDT",
"Etc/GMT",
"Etc/GMT+1",
"Etc/GMT+10",
"Etc/GMT+11",
"Etc/GMT+12",
"Etc/GMT+2",
"Etc/GMT+3",
"Etc/GMT+4",
"Etc/GMT+5",
"Etc/GMT+6",
"Etc/GMT+7",
"Etc/GMT-1",
"Etc/GMT-10",
"Etc/GMT-11",
"Etc/GMT-12",
"Etc/GMT-13",
"Etc/GMT-2",
"Etc/GMT-3",
"Etc/GMT-4",
"Etc/GMT-5",
"Etc/GMT-6",
"Etc/GMT-7",
"Etc/GMT-8",
"Etc/GMT-9",
"Europe/Amsterdam",
"Europe/Andorra",
"Europe/Astrakhan",
"Europe/Athens",
"Europe/Belgrade",
"Europe/Berlin",
"Europe/Bratislava",
"Europe/Brussels",
"Europe/Bucharest",
"Europe/Budapest",
"Europe/Busingen",
"Europe/Chisinau",
"Europe/Copenhagen",
"Europe/Dublin",
"Europe/Gibraltar",
"Europe/Guernsey",
"Europe/Helsinki",
"Europe/Isle_of_Man",
"Europe/Istanbul",
"Europe/Jersey",
"Europe/Kaliningrad",
"Europe/Kiev",
"Europe/Kirov",
"Europe/Lisbon",
"Europe/Ljubljana",
"Europe/London",
"Europe/Luxembourg",
"Europe/Madrid",
"Europe/Malta",
"Europe/Mariehamn",
"Europe/Minsk",
"Europe/Monaco",
"Europe/Moscow",
"Europe/Nicosia",
"Europe/Oslo",
"Europe/Paris",
"Europe/Podgorica",
"Europe/Prague",
"Europe/Riga",
"Europe/Rome",
"Europe/Samara",
"Europe/San_Marino",
"Europe/Sarajevo",
"Europe/Simferopol",
"Europe/Skopje",
"Europe/Sofia",
"Europe/Stockholm",
"Europe/Tallinn",
"Europe/Tirane",
"Europe/Ulyanovsk",
"Europe/Uzhgorod",
"Europe/Vaduz",
"Europe/Vatican",
"Europe/Vienna",
"Europe/Vilnius",
"Europe/Volgograd",
"Europe/Warsaw",
"Europe/Zagreb",
"Europe/Zaporozhye",
"Europe/Zurich",
"Indian/Antananarivo",
"Indian/Chagos",
"Indian/Christmas",
"Indian/Cocos",
"Indian/Comoro",
"Indian/Kerguelen",
"Indian/Mahe",
"Indian/Maldives",
"Indian/Mauritius",
"Indian/Mayotte",
"Indian/Reunion",
"MST7MDT",
"PST8PDT",
"Pacific/Apia",
"Pacific/Auckland",
"Pacific/Efate",
"Pacific/Enderbury",
"Pacific/Fakaofo",
"Pacific/Fiji",
"Pacific/Funafuti",
"Pacific/Galapagos",
"Pacific/Guadalcanal",
"Pacific/Guam",
"Pacific/Honolulu",
"Pacific/Johnston",
"Pacific/Kosrae",
"Pacific/Kwajalein",
"Pacific/Majuro",
"Pacific/Midway",
"Pacific/Nauru",
"Pacific/Niue",
"Pacific/Noumea",
"Pacific/Pago_Pago",
"Pacific/Palau",
"Pacific/Ponape",
"Pacific/Port_Moresby",
"Pacific/Rarotonga",
"Pacific/Saipan",
"Pacific/Tahiti",
"Pacific/Tarawa",
"Pacific/Tongatapu",
"Pacific/Truk",
"Pacific/Wake",
"Pacific/Wallis",
]
Note that any mapping from "Name" to anything (even text) wouldn't be unique -- e.g. America/Los_Angeles appears in two entries for with and without DST here.
The output of this can be dumped into a JSON5 file (last line has comment) and stored in your repo. You can run this script every now and then to get updated list.
A more detailed script that I wrote and I am actually going to store for generating this code is avaiable at: https://gist.github.com/eyedean/18f2611624c8f9624f8bc6a3b74e9dba