add timezone to date javascript

How to initialize a JavaScript Date to a particular time zone

stackoverflow.com › questions › 15141762 › how-to-initialize-a-javascript-date-to-a-particular-time-zone

Background

JavaScript's Date object tracks time in UTC internally, but typically accepts input and produces output in the local time of the computer it's running on. It has very few facilities for working with time in other time zones.

The internal representation of a Date object is a single number - namely timestamp - representing the number of milliseconds that have elapsed since 1970-01-01 00:00:00 UTC, without regard to leap seconds.

There is no time zone or string format stored in the Date object itself.

When various functions of the Date object are used, the computer's local time zone is applied to the internal representation. If the function produces a string, then the computer's locale information may be taken into consideration to determine how to produce that string. The details vary per function, and some are implementation-specific.

The only operations the Date object can do with non-local time zones are:

It can parse a string containing a numeric UTC offset from any time zone. It uses this to adjust the value being parsed, and stores the UTC equivalent. The original local time and offset are not retained in the resulting Date object. For example:
```
  var d = new Date("2020-04-13T00:00:00.000+08:00");
  d.toISOString()  //=> "2020-04-12T16:00:00.000Z"
  d.valueOf()      //=> 1586707200000  (this is what is actually stored in the object)
```
In environments that have implemented the ECMASCript Internationalization API (aka "Intl"), a Date object can produce a locale-specific string adjusted to a given time zone identifier. This is accomplished via the timeZone option to toLocaleString and its variations. Most implementations will support IANA time zone identifiers, such as 'America/New_York'. For example:
```
  var d = new Date("2020-04-13T00:00:00.000+08:00");
  d.toLocaleString('en-US', { timeZone: 'America/New_York' })
  //=> "4/12/2020, 12:00:00 PM"
  // (midnight in China on April 13th is noon in New York on April 12th)
```
Most modern environments support the full set of IANA time zone identifiers (see the compatibility table here). However, keep in mind that the only identifier required to be supported by Intl is 'UTC', thus you should check carefully if you need to support older browsers or atypical environments (for example, lightweight IoT devices).

Libraries

There are several libraries that can be used to work with time zones. Though they still cannot make the Date object behave any differently, they typically implement the standard IANA timezone database and provide functions for using it in JavaScript. Modern libraries use the time zone data supplied by the Intl API, but older libraries typically have overhead, especially if you are running in a web browser, as the database can get a bit large. Some of these libraries also allow you to selectively reduce the data set, either by which time zones are supported and/or by the range of dates you can work with.

Here are the libraries to consider:

Intl-based Libraries

New development should choose from one of these implementations, which rely on the Intl API for their time zone data:

Luxon (successor of Moment.js)
date-fns-tz (extension for date-fns)
Day.js (when using its Timezone plugin)

Non-Intl Libraries

These libraries are maintained, but carry the burden of packaging their own time zone data, which can be quite large.

js-joda/timezone (extension for js-joda)
moment-timezone* (extension for Moment.js)
date-fns-timezone (extension for older 1.x of date-fns)
BigEasy/TimeZone
tz.js

* While Moment and Moment-Timezone were previously recommended, the Moment team now prefers users chose Luxon for new development.

Discontinued Libraries

These libraries have been officially discontinued and should no longer be used.

WallTime-js
TimeZoneJS

Future Proposals

The TC39 Temporal Proposal aims to provide a new set of standard objects for working with dates and times in the JavaScript language itself. This will include support for a time zone aware object.

Common Errors

There are several approaches that are often tried, which are in error and should usually be avoided.

Re-Parsing

new Date(new Date().toLocaleString('en', {timeZone: 'America/New_York'}))

The above approach correctly uses the Intl API to create a string in a specific time zone, but then it incorrectly passes that string back into the Date constructor. In this case, parsing will be implementation-specific, and may fail entirely. If successful, it is likely that the resulting Date object now represents the wrong instant in time, as the computer's local time zone would be applied during parsing.

Epoch Shifting

var d = new Date();
d.setTime(d.getTime() + someOffset * 60000);

The above approach attempts to manipulate the Date object's time zone by shifting the Unix timestamp by some other time zone offset. However, since the Date object only tracks time in UTC, it actually just makes the Date object represent a different point in time.

The same approach is sometimes used directly on the constructor, and is also invalid.

Epoch Shifting is sometimes used internally in date libraries as a shortcut to avoid writing calendar arithmetic. When doing so, any access to non-UTC properties must be avoided. For example, once shifted, a call to getUTCHours would be acceptable, but a call to getHours would be invalid because it uses the local time zone.

It is called "epoch shifting", because when used correctly, the Unix Epoch (1970-01-01T00:00:00.000Z) is now no longer correlated to a timestamp of 0 but has shifted to a different timestamp by the amount of the offset.

If you're not authoring a date library, you should not be epoch shifting.

For more details about epoch shifting, watch this video clip from Greg Miller at CppCon 2015. The video is about time_t in C++, but the explanation and problems are identical. (For JavaScript folks, every time you hear Greg mention time_t, just think "Date object".)

Trying to make a "UTC Date"

var d = new Date();
var utcDate = new Date(Date.UTC(d.getUTCFullYear(), d.getUTCMonth(), d.getUTCDate(), d.getUTCHours(), d.getUTCMinutes(), d.getUTCSeconds(), d.getUTCMilliseconds()));

In this example, both d and utcDate are identical. The work to construct utcDate was redundant, because d is already in terms of UTC. Examining the output of toISOString, getTime, or valueOf functions will show identical values for both variables.

A similar approach seen is:

var d = new Date();
var utcDate = new Date(d.getUTCFullYear(), d.getUTCMonth(), d.getUTCDate(), d.getUTCHours(), d.getUTCMinutes(), d.getUTCSeconds(), d.getUTCMilliseconds());

This is approach passes UTC values into the Date constructor where local time values are expected. The resulting Date object now represents a completely different point in time. It is essentially the same result as epoch shifting described earlier, and thus should be avoided.

The correct way to get a UTC-based Date object is simply new Date(). If you need a string representation that is in UTC, then use new Date().toISOString().

Answer from Matt Johnson-Pint on Stack Overflow

Stack Overflow

stackoverflow.com › questions › 15141762 › how-to-initialize-a-javascript-date-to-a-particular-time-zone

timezone - How to initialize a JavaScript Date to a particular time zone - Stack Overflow

Top answer

1 of 16

969

Background

JavaScript's Date object tracks time in UTC internally, but typically accepts input and produces output in the local time of the computer it's running on. It has very few facilities for working with time in other time zones.

The internal representation of a Date object is a single number - namely timestamp - representing the number of milliseconds that have elapsed since 1970-01-01 00:00:00 UTC, without regard to leap seconds.

There is no time zone or string format stored in the Date object itself.

When various functions of the Date object are used, the computer's local time zone is applied to the internal representation. If the function produces a string, then the computer's locale information may be taken into consideration to determine how to produce that string. The details vary per function, and some are implementation-specific.

The only operations the Date object can do with non-local time zones are:

It can parse a string containing a numeric UTC offset from any time zone. It uses this to adjust the value being parsed, and stores the UTC equivalent. The original local time and offset are not retained in the resulting Date object. For example:
```
  var d = new Date("2020-04-13T00:00:00.000+08:00");
  d.toISOString()  //=> "2020-04-12T16:00:00.000Z"
  d.valueOf()      //=> 1586707200000  (this is what is actually stored in the object)
```
In environments that have implemented the ECMASCript Internationalization API (aka "Intl"), a Date object can produce a locale-specific string adjusted to a given time zone identifier. This is accomplished via the timeZone option to toLocaleString and its variations. Most implementations will support IANA time zone identifiers, such as 'America/New_York'. For example:
```
  var d = new Date("2020-04-13T00:00:00.000+08:00");
  d.toLocaleString('en-US', { timeZone: 'America/New_York' })
  //=> "4/12/2020, 12:00:00 PM"
  // (midnight in China on April 13th is noon in New York on April 12th)
```
Most modern environments support the full set of IANA time zone identifiers (see the compatibility table here). However, keep in mind that the only identifier required to be supported by Intl is 'UTC', thus you should check carefully if you need to support older browsers or atypical environments (for example, lightweight IoT devices).

Libraries

There are several libraries that can be used to work with time zones. Though they still cannot make the Date object behave any differently, they typically implement the standard IANA timezone database and provide functions for using it in JavaScript. Modern libraries use the time zone data supplied by the Intl API, but older libraries typically have overhead, especially if you are running in a web browser, as the database can get a bit large. Some of these libraries also allow you to selectively reduce the data set, either by which time zones are supported and/or by the range of dates you can work with.

Here are the libraries to consider:

Intl-based Libraries

New development should choose from one of these implementations, which rely on the Intl API for their time zone data:

Luxon (successor of Moment.js)
date-fns-tz (extension for date-fns)
Day.js (when using its Timezone plugin)

Non-Intl Libraries

These libraries are maintained, but carry the burden of packaging their own time zone data, which can be quite large.

js-joda/timezone (extension for js-joda)
moment-timezone* (extension for Moment.js)
date-fns-timezone (extension for older 1.x of date-fns)
BigEasy/TimeZone
tz.js

* While Moment and Moment-Timezone were previously recommended, the Moment team now prefers users chose Luxon for new development.

Discontinued Libraries

These libraries have been officially discontinued and should no longer be used.

WallTime-js
TimeZoneJS

Future Proposals

The TC39 Temporal Proposal aims to provide a new set of standard objects for working with dates and times in the JavaScript language itself. This will include support for a time zone aware object.

Common Errors

There are several approaches that are often tried, which are in error and should usually be avoided.

Re-Parsing

new Date(new Date().toLocaleString('en', {timeZone: 'America/New_York'}))

The above approach correctly uses the Intl API to create a string in a specific time zone, but then it incorrectly passes that string back into the Date constructor. In this case, parsing will be implementation-specific, and may fail entirely. If successful, it is likely that the resulting Date object now represents the wrong instant in time, as the computer's local time zone would be applied during parsing.

Epoch Shifting

var d = new Date();
d.setTime(d.getTime() + someOffset * 60000);

The above approach attempts to manipulate the Date object's time zone by shifting the Unix timestamp by some other time zone offset. However, since the Date object only tracks time in UTC, it actually just makes the Date object represent a different point in time.

The same approach is sometimes used directly on the constructor, and is also invalid.

Epoch Shifting is sometimes used internally in date libraries as a shortcut to avoid writing calendar arithmetic. When doing so, any access to non-UTC properties must be avoided. For example, once shifted, a call to getUTCHours would be acceptable, but a call to getHours would be invalid because it uses the local time zone.

It is called "epoch shifting", because when used correctly, the Unix Epoch (1970-01-01T00:00:00.000Z) is now no longer correlated to a timestamp of 0 but has shifted to a different timestamp by the amount of the offset.

If you're not authoring a date library, you should not be epoch shifting.

For more details about epoch shifting, watch this video clip from Greg Miller at CppCon 2015. The video is about time_t in C++, but the explanation and problems are identical. (For JavaScript folks, every time you hear Greg mention time_t, just think "Date object".)

Trying to make a "UTC Date"

var d = new Date();
var utcDate = new Date(Date.UTC(d.getUTCFullYear(), d.getUTCMonth(), d.getUTCDate(), d.getUTCHours(), d.getUTCMinutes(), d.getUTCSeconds(), d.getUTCMilliseconds()));

In this example, both d and utcDate are identical. The work to construct utcDate was redundant, because d is already in terms of UTC. Examining the output of toISOString, getTime, or valueOf functions will show identical values for both variables.

A similar approach seen is:

var d = new Date();
var utcDate = new Date(d.getUTCFullYear(), d.getUTCMonth(), d.getUTCDate(), d.getUTCHours(), d.getUTCMinutes(), d.getUTCSeconds(), d.getUTCMilliseconds());

This is approach passes UTC values into the Date constructor where local time values are expected. The resulting Date object now represents a completely different point in time. It is essentially the same result as epoch shifting described earlier, and thus should be avoided.

The correct way to get a UTC-based Date object is simply new Date(). If you need a string representation that is in UTC, then use new Date().toISOString().

2 of 16

250

As Matt Johnson said

If you can limit your usage to modern web browsers, you can now do the following without any special libraries:

new Date().toLocaleString("en-US", {timeZone: "America/New_York"})

This isn't a comprehensive solution, but it works for many scenarios that require only output conversion (from UTC or local time to a specific time zone, but not the other direction).

So although the browser can not read IANA timezones when creating a date, or has any methods to change the timezones on an existing Date object, there seems to be a hack around it.

Consider the following function

function changeTimezone(date, ianatz) {

  // suppose the date is 12:00 UTC
  var invdate = new Date(date.toLocaleString('en-US', {
    timeZone: ianatz
  }));

  // then invdate will be 07:00 in Toronto
  // and the diff is 5 hours
  var diff = date.getTime() - invdate.getTime();

  // so 12:00 in Toronto is 17:00 UTC
  return new Date(date.getTime() - diff); // needs to substract

}

However, closely looking at the return value, this can be simplified to:

function changeTimezone(date, ianatz) {
  return new Date(date.toLocaleString('en-US', {
    timeZone: ianatz
  }));
}

// E.g.
var here = new Date();
var there = changeTimezone(here, "America/Toronto");

console.log(`Here: ${here.toString()}\nToronto: ${there.toString()}`);

CoreUI

coreui.io › blog › how-to-manage-date-and-time-in-specific-timezones-using-javascript

How to Manage Date and Time in Specific Timezones Using JavaScript · CoreUI

January 22, 2025 - These libraries handle complex cases like daylight saving transitions and support a wide range of timezone data. For date input and selection in forms, explore the CoreUI React Date Picker or Bootstrap Date Picker for intuitive and customizable solutions. When building global applications, you often need to schedule events for users in different regions. JavaScript’s Intl.DateTimeFormat API can dynamically adjust for the user’s local timezone.

Stack Overflow

stackoverflow.com › questions › 439630 › create-a-date-with-a-set-timezone-without-using-a-string-representation

javascript - Create a Date with a set timezone without using a string representation - Stack Overflow

Top answer

1 of 16

568

using .setUTCHours() it would be possible to actually set dates in UTC-time, which would allow you to use UTC-times throughout the system.

You cannot set it using UTC in the constructor though, unless you specify a date-string.

Using new Date(Date.UTC(year, month, day, hour, minute, second)) you can create a Date-object from a specific UTC time.

2 of 16

298

Simply Set the Time Zone and Get Back According

new Date().toLocaleString("en-US", {timeZone: "America/New_York"})

Other Time-zones are as Following

var world_timezones =
[
    'Europe/Andorra',
    'Asia/Dubai',
    'Asia/Kabul',
    'Europe/Tirane',
    'Asia/Yerevan',
    'Antarctica/Casey',
    'Antarctica/Davis',
    'Antarctica/DumontDUrville', 
    'Antarctica/Mawson',
    'Antarctica/Palmer',
    'Antarctica/Rothera',
    'Antarctica/Syowa',
    'Antarctica/Troll',
    'Antarctica/Vostok',
    'America/Argentina/Buenos_Aires',
    'America/Argentina/Cordoba',
    'America/Argentina/Salta',
    'America/Argentina/Jujuy',
    'America/Argentina/Tucuman',
    'America/Argentina/Catamarca',
    'America/Argentina/La_Rioja',
    'America/Argentina/San_Juan',
    'America/Argentina/Mendoza',
    'America/Argentina/San_Luis',
    'America/Argentina/Rio_Gallegos',
    'America/Argentina/Ushuaia',
    'Pacific/Pago_Pago',
    'Europe/Vienna',
    'Australia/Lord_Howe',
    'Antarctica/Macquarie',
    'Australia/Hobart',
    'Australia/Currie',
    'Australia/Melbourne',
    'Australia/Sydney',
    'Australia/Broken_Hill',
    'Australia/Brisbane',
    'Australia/Lindeman',
    'Australia/Adelaide',
    'Australia/Darwin',
    'Australia/Perth',
    'Australia/Eucla',
    'Asia/Baku',
    'America/Barbados',
    'Asia/Dhaka',
    'Europe/Brussels',
    'Europe/Sofia',
    'Atlantic/Bermuda',
    'Asia/Brunei',
    'America/La_Paz',
    'America/Noronha',
    'America/Belem',
    'America/Fortaleza',
    'America/Recife',
    'America/Araguaina',
    'America/Maceio',
    'America/Bahia',
    'America/Sao_Paulo',
    'America/Campo_Grande',
    'America/Cuiaba',
    'America/Santarem',
    'America/Porto_Velho',
    'America/Boa_Vista',
    'America/Manaus',
    'America/Eirunepe',
    'America/Rio_Branco',
    'America/Nassau',
    'Asia/Thimphu',
    'Europe/Minsk',
    'America/Belize',
    'America/St_Johns',
    'America/Halifax',
    'America/Glace_Bay',
    'America/Moncton',
    'America/Goose_Bay',
    'America/Blanc-Sablon',
    'America/Toronto',
    'America/Nipigon',
    'America/Thunder_Bay',
    'America/Iqaluit',
    'America/Pangnirtung',
    'America/Atikokan',
    'America/Winnipeg',
    'America/Rainy_River',
    'America/Resolute',
    'America/Rankin_Inlet',
    'America/Regina',
    'America/Swift_Current',
    'America/Edmonton',
    'America/Cambridge_Bay',
    'America/Yellowknife',
    'America/Inuvik',
    'America/Creston',
    'America/Dawson_Creek',
    'America/Fort_Nelson',
    'America/Vancouver',
    'America/Whitehorse',
    'America/Dawson',
    'Indian/Cocos',
    'Europe/Zurich',
    'Africa/Abidjan',
    'Pacific/Rarotonga',
    'America/Santiago',
    'America/Punta_Arenas',
    'Pacific/Easter',
    'Asia/Shanghai',
    'Asia/Urumqi',
    'America/Bogota',
    'America/Costa_Rica',
    'America/Havana',
    'Atlantic/Cape_Verde',
    'America/Curacao',
    'Indian/Christmas',
    'Asia/Nicosia',
    'Asia/Famagusta',
    'Europe/Prague',
    'Europe/Berlin',
    'Europe/Copenhagen',
    'America/Santo_Domingo',
    'Africa/Algiers',
    'America/Guayaquil',
    'Pacific/Galapagos',
    'Europe/Tallinn',
    'Africa/Cairo',
    'Africa/El_Aaiun',
    'Europe/Madrid',
    'Africa/Ceuta',
    'Atlantic/Canary',
    'Europe/Helsinki',
    'Pacific/Fiji',
    'Atlantic/Stanley',
    'Pacific/Chuuk',
    'Pacific/Pohnpei',
    'Pacific/Kosrae',
    'Atlantic/Faroe',
    'Europe/Paris',
    'Europe/London',
    'Asia/Tbilisi',
    'America/Cayenne',
    'Africa/Accra',
    'Europe/Gibraltar',
    'America/Godthab',
    'America/Danmarkshavn',
    'America/Scoresbysund',
    'America/Thule',
    'Europe/Athens',
    'Atlantic/South_Georgia',
    'America/Guatemala',
    'Pacific/Guam',
    'Africa/Bissau',
    'America/Guyana',
    'Asia/Hong_Kong',
    'America/Tegucigalpa',
    'America/Port-au-Prince',
    'Europe/Budapest',
    'Asia/Jakarta',
    'Asia/Pontianak',
    'Asia/Makassar',
    'Asia/Jayapura',
    'Europe/Dublin',
    'Asia/Jerusalem',
    'Asia/Kolkata',
    'Indian/Chagos',
    'Asia/Baghdad',
    'Asia/Tehran',
    'Atlantic/Reykjavik',
    'Europe/Rome',
    'America/Jamaica',
    'Asia/Amman',
    'Asia/Tokyo',
    'Africa/Nairobi',
    'Asia/Bishkek',
    'Pacific/Tarawa',
    'Pacific/Enderbury',
    'Pacific/Kiritimati',
    'Asia/Pyongyang',
    'Asia/Seoul',
    'Asia/Almaty',
    'Asia/Qyzylorda',
    'Asia/Qostanay', 
    'Asia/Aqtobe',
    'Asia/Aqtau',
    'Asia/Atyrau',
    'Asia/Oral',
    'Asia/Beirut',
    'Asia/Colombo',
    'Africa/Monrovia',
    'Europe/Vilnius',
    'Europe/Luxembourg',
    'Europe/Riga',
    'Africa/Tripoli',
    'Africa/Casablanca',
    'Europe/Monaco',
    'Europe/Chisinau',
    'Pacific/Majuro',
    'Pacific/Kwajalein',
    'Asia/Yangon',
    'Asia/Ulaanbaatar',
    'Asia/Hovd',
    'Asia/Choibalsan',
    'Asia/Macau',
    'America/Martinique',
    'Europe/Malta',
    'Indian/Mauritius',
    'Indian/Maldives',
    'America/Mexico_City',
    'America/Cancun',
    'America/Merida',
    'America/Monterrey',
    'America/Matamoros',
    'America/Mazatlan',
    'America/Chihuahua',
    'America/Ojinaga',
    'America/Hermosillo',
    'America/Tijuana',
    'America/Bahia_Banderas',
    'Asia/Kuala_Lumpur',
    'Asia/Kuching',
    'Africa/Maputo',
    'Africa/Windhoek',
    'Pacific/Noumea',
    'Pacific/Norfolk',
    'Africa/Lagos',
    'America/Managua',
    'Europe/Amsterdam',
    'Europe/Oslo',
    'Asia/Kathmandu',
    'Pacific/Nauru',
    'Pacific/Niue',
    'Pacific/Auckland',
    'Pacific/Chatham',
    'America/Panama',
    'America/Lima',
    'Pacific/Tahiti',
    'Pacific/Marquesas',
    'Pacific/Gambier',
    'Pacific/Port_Moresby',
    'Pacific/Bougainville',
    'Asia/Manila',
    'Asia/Karachi',
    'Europe/Warsaw',
    'America/Miquelon',
    'Pacific/Pitcairn',
    'America/Puerto_Rico',
    'Asia/Gaza',
    'Asia/Hebron',
    'Europe/Lisbon',
    'Atlantic/Madeira',
    'Atlantic/Azores',
    'Pacific/Palau',
    'America/Asuncion',
    'Asia/Qatar',
    'Indian/Reunion',
    'Europe/Bucharest',
    'Europe/Belgrade',
    'Europe/Kaliningrad',
    'Europe/Moscow',
    'Europe/Simferopol',
    'Europe/Kirov',
    'Europe/Astrakhan',
    'Europe/Volgograd',
    'Europe/Saratov',
    'Europe/Ulyanovsk',
    'Europe/Samara',
    'Asia/Yekaterinburg',
    'Asia/Omsk',
    'Asia/Novosibirsk',
    'Asia/Barnaul',
    'Asia/Tomsk',
    'Asia/Novokuznetsk',
    'Asia/Krasnoyarsk',
    'Asia/Irkutsk',
    'Asia/Chita',
    'Asia/Yakutsk',
    'Asia/Khandyga',
    'Asia/Vladivostok',
    'Asia/Ust-Nera',
    'Asia/Magadan',
    'Asia/Sakhalin',
    'Asia/Srednekolymsk',
    'Asia/Kamchatka',
    'Asia/Anadyr',
    'Asia/Riyadh',
    'Pacific/Guadalcanal',
    'Indian/Mahe',
    'Africa/Khartoum',
    'Europe/Stockholm',
    'Asia/Singapore',
    'America/Paramaribo',
    'Africa/Juba',
    'Africa/Sao_Tome',
    'America/El_Salvador',
    'Asia/Damascus',
    'America/Grand_Turk',
    'Africa/Ndjamena',
    'Indian/Kerguelen',
    'Asia/Bangkok',
    'Asia/Dushanbe',
    'Pacific/Fakaofo',
    'Asia/Dili',
    'Asia/Ashgabat',
    'Africa/Tunis',
    'Pacific/Tongatapu',
    'Europe/Istanbul',
    'America/Port_of_Spain',
    'Pacific/Funafuti',
    'Asia/Taipei',
    'Europe/Kiev',
    'Europe/Uzhgorod',
    'Europe/Zaporozhye',
    'Pacific/Wake',
    'America/New_York',
    'America/Detroit',
    'America/Kentucky/Louisville',
    'America/Kentucky/Monticello',
    'America/Indiana/Indianapolis',
    'America/Indiana/Vincennes',
    'America/Indiana/Winamac',
    'America/Indiana/Marengo',
    'America/Indiana/Petersburg',
    'America/Indiana/Vevay',
    'America/Chicago',
    'America/Indiana/Tell_City',
    'America/Indiana/Knox',
    'America/Menominee',
    'America/North_Dakota/Center',
    'America/North_Dakota/New_Salem',
    'America/North_Dakota/Beulah',
    'America/Denver',
    'America/Boise',
    'America/Phoenix',
    'America/Los_Angeles',
    'America/Anchorage',
    'America/Juneau',
    'America/Sitka',
    'America/Metlakatla',
    'America/Yakutat',
    'America/Nome',
    'America/Adak',
    'Pacific/Honolulu',
    'America/Montevideo',
    'Asia/Samarkand',
    'Asia/Tashkent',
    'America/Caracas',
    'Asia/Ho_Chi_Minh',
    'Pacific/Efate',
    'Pacific/Wallis',
    'Pacific/Apia',
    'Africa/Johannesburg'
];

Jaketrent

jaketrent.com › post › set-timezone-javascript-date

Set Timezone by Name in JavaScript Date

What we're trying to do is to create the Date in a named IANA timezone (eg, 'America/New_York') other than that of the runtime environment. The tl;dr on successfully setting the timezone is: Set it when the Date is instantiated, don't adjust it. There is no one-line native-JavaScript API available to set the Timezone by name at the time of creation.

Bobby Hadz

bobbyhadz.com › blog › javascript-initialize-date-with-timezone

How to initialize JavaScript Date to a Particular Time Zone | bobbyhadz

Use the `toLocaleString()` method to initialize a date with a time zone in JavaScript.

Stack Overflow

stackoverflow.com › questions › 7403486 › add-or-subtract-timezone-difference-to-javascript-date

add or subtract timezone difference to javascript Date - Stack Overflow

Top answer

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You can use Date.getTimezoneOffset which returns the local offset from GMT in minutes. Note that it returns the value with the opposite sign you might expect. So GMT-5 is 300 and GMT+1 is -60.

var date = "September 21, 2011 00:00:00";
var targetTime = new Date(date);
var timeZoneFromDB = -7.00; //time zone value from database
//get the timezone offset from local time in minutes
var tzDifference = timeZoneFromDB * 60 + targetTime.getTimezoneOffset();
//convert the offset to milliseconds, add to targetTime, and make a new Date
var offsetTime = new Date(targetTime.getTime() + tzDifference * 60 * 1000);

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37

Simple function that works for me:

adjustForTimezone(date:Date):Date{
    var timeOffsetInMS:number = date.getTimezoneOffset() * 60000;
    date.setTime(date.getTime() + timeOffsetInMS);
    return date
}

SheCodes

shecodes.io › athena › 8564-setting-date-time-in-a-specific-timezone-in-javascript

[JavaScript] - Setting Date & Time in a Specific Timezone in JavaScript

Learn how to set the date & time in a specific timezone in Javascript by defining the required timezone and adjusting the timezone offset. List of valid IANA Time Zone database included.

Medium

toastui.medium.com › handling-time-zone-in-javascript-547e67aa842d

Handling Time Zone in JavaScript. Recently, I worked on a task of adding… | by TOAST UI | Medium

August 30, 2019 - Now we’re ready to use a well built library. Moment is a well established JavaScript library that is almost the standard for processing date. Providing a variety of date and formatting APIs, it is recognized by so many users recently as stable and reliable. And there is Moment Timezone, an extension module, that solves all the problems discussed above.

MDN Web Docs

developer.mozilla.org › en-US › docs › Web › JavaScript › Reference › Global_Objects › Date › getTimezoneOffset

Date.prototype.getTimezoneOffset() - JavaScript | MDN

const shModernOffset = new Date("2022-01-27").getTimezoneOffset(); // -480 const shHistoricalOffset = new Date("1943-01-27").getTimezoneOffset(); // -540 · This is because during the Sino-Japanese War when Shanghai was under Japanese control, the timezone was changed to UTC+09:00 to align with Japan's (in effect, it was a "year-round DST"), and this was recorded in the IANA database.

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Ursahealth

ursahealth.com › new-insights › dates-and-timezones-in-javascript

Working with dates and timezones in JavaScript: a survival guide

May 4, 2021 - On the other hand, you cannot easily code your way out of the server timezone localization, because this has already been baked into the universal time of the JavaScript date. So you really do need to know the timezone of the server, which is work that needs to be done server-side. Resist the temptation to assume that you know the server’s timezone! Not only would that solution not be portable, but in the United States your server’s timezone is going to change twice a year, when daylight savings time hits. Rather, convince the back-end devs to add an endpoint to show the timezone of the server.

Netlify

netlify.com › blog › how-to-get-timezone-in-javascript-with-edge-functions

How to get the user‘s timezone in JavaScript with Edge Functions

You don‘t need client-side JavaScript to adapt and localize dates and times according to timezone — use timezone data in Netlify Edge Functions with JavaScript native Date()!

Plain English

plainenglish.io › blog › how-to-initialize-a-javascript-date-to-a-particular-time-zone-a03969601c58

How to Initialize a JavaScript Date to a Particular Time Zone?

We can add the time zone info to the end of the date string that we use to create the Date object. ... The +08:00 part means that the date string we have is 8 hours ahead of UTC. ... The JavaScrip date object has the toLocaleString method to ...

reddit.com › r/learnjavascript › date object and timezones stuff

r/learnjavascript on Reddit: Date object and timezones stuff

February 6, 2024 -

when I set a date using a calander libary and save it in my localstorage as date.toISOString().split("T")[0] and after reloading the page, I retrieve from the localstorage and set in my local variable with new Date(date), it sets the time 1 day backward. I'm guessing its because the timezone i'm using is US and since US is 7 hours behind UTC, so new Date() treats the argument as a UTC time and converts it into a local time?, how do I configure it to give me the exact date I stored in my localstorage?

Top answer

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2

You are correct that JavaScript looks at new Date(‘2024-02-06’) and coverts it based on the time as 00:00:00 GMT, so it is the same as new Date(‘2024-02-06T00:00:00Z’) If you add “00:00:00” to your date string it should work. Example “new Date(‘2024-02-06 00:00:00’)” will be February 6, 2024 at 12:00am for all users regardless of their time zone. If I recall correctly you can also change your date string format to mm/dd/yyyy and it will covert as you expect with new Date. So new Date(‘02/06/2024’) would also be February 6, 2024 for all users regardless of time zone.

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Hmm that sounds a little bit puzzling. You are correct that everything Date in Js is basically UTC. According to the following code, it basically works as I would expect. Is there anything that you are doing differently? const date = new Date(); const currentDate = date.toISOString().split("T")[0]; // "2024-02-06" // pretend to save to localStorage, reload and retrieve const fromLocalStorage = currentDate // "2024-02-06"; const savedDate = new Date(Date.parse(fromLocalStorage)); // "2024-02-06T00:00:00.000Z";

W3Schools

w3schools.com › jsref › jsref_gettimezoneoffset.asp

JavaScript Date getTimezoneOffset() Method

W3Schools offers free online tutorials, references and exercises in all the major languages of the web. Covering popular subjects like HTML, CSS, JavaScript, Python, SQL, Java, and many, many more.

MDN Web Docs

developer.mozilla.org › en-US › docs › Web › JavaScript › Reference › Global_Objects › Date

Date - JavaScript | MDN

Defaults to 000. Z is the timezone offset, which can either be the literal character Z (indicating UTC), or + or - followed by HH:mm, the offset in hours and minutes from UTC. Various components can be omitted, so the following are all valid: ... Date-time form: one of the above date-only forms, followed by T, followed by HH:mm, HH:mm:ss, or HH:mm:ss.sss.

Heady

heady.io › blog › javascript-handle-date-in-any-timezone-with-daylight-saving-check

Handle Dates in any Timezone with Javascript

The most common method for adding a date to your application is JavaScript Date. If you want today’s date, you can simply write the following line. This will give you a new object with the current date and time, in your specific timezone.

GeeksforGeeks

geeksforgeeks.org › javascript › how-to-convert-date-to-another-timezone-in-javascript

How to Convert Date to Another Timezone in JavaScript? - GeeksforGeeks

July 12, 2025 - This ensures that the displayed time aligns with the selected timezone, often using built-in methods or external libraries. Intl.DateTimeFormat() in JavaScript allows formatting dates according to a specific locale and timezone.

Go Make Things

gomakethings.com › getting-a-date-in-the-current-users-timezone-with-javascript

Getting a date in the current user's timezone with JavaScript | Go Make Things

Next, we’ll use the Date.now() method to get a Unix timestamp for right now in the current user’s timezone.

Delft Stack

delftstack.com › home › howto › javascript › initialize javascript date to a particular timezone

How to Initialize JavaScript Date to a Particular Time Zone | Delft Stack

February 2, 2024 - JavaScript’s date object works with UTC internally but displays output according to the local time of the operating computer. The date object doesn’t have any notion of time zones. There are no string objects declared. It is just a measurement of the number of milliseconds that have elapsed since 1970-01-01 00:00:00 UTC.

MDN Web Docs

developer.mozilla.org › en-US › docs › Web › JavaScript › Reference › Global_Objects › Date › toLocaleTimeString

Date.prototype.toLocaleTimeString() - JavaScript | MDN

When the method is called many times with the same arguments, it is better to create an Intl.DateTimeFormat object and use its format() method, because a DateTimeFormat object remembers the arguments passed to it and may decide to cache a slice of the database, so future format calls can search for localization strings within a more constrained context. // Depending on timezone, your results will vary const event = new Date("August 19, 1975 23:15:30 GMT+00:00"); console.log(event.toLocaleTimeString("en-US")); // Expected output: "1:15:30 AM" console.log(event.toLocaleTimeString("it-IT")); // Expected output: "01:15:30" console.log(event.toLocaleTimeString("ar-EG")); // Expected output: "١٢:١٥:٣٠ ص"