Moment Timezone Documentation

To use moment-timezone, you will need [email protected]+, moment-timezone.js, and the moment-timezone data.

For convenience, there are builds available on momentjs.com/timezone/ with all the zone data or a subset of the data.

• moment-timezone-with-data.js is recommended for server environments (Node.js) and covers all years available.
• moment-timezone-with-data-10-year-range.js is recommend for most browser environments, covering +/- 5 years from the year published.
• moment-timezone-with-data-1970-2030.js covers a 60 year range, for those that need more data but not the larger file size of the full data file.

If you use one of the above files, you still need moment.js, but you do not need moment-timezone.js because it is included.

npm install moment-timezone

In Node.js, all the data is preloaded. No additional code is needed for loading data.

var moment = require('moment-timezone');
moment().tz("America/Los_Angeles").format();

In ECMAScript native module format (or in TypeScript):

import moment from 'moment-timezone';
moment().tz("America/Los_Angeles").format();

Note: You don't need to require/import the base moment library as well. Moment Timezone will automatically load and extend the moment module, then return the modified instance.

Package managers like npm and yarn can sometimes create situations where multiple versions of moment are installed. Importing only from moment-timezone can help ensure that the same version is used consistently. See this comment on issue #982 for a much more detailed explanation, including steps to fix potential versioning problems.

// Unnecessary, can cause issues with package managers
import moment from 'moment';
import 'moment-timezone';

// Correct
import moment from 'moment-timezone';

The pre-built bundles are also included in the npm package, and can be loaded directly. These allow you to import the library with a smaller subset of data.

import moment from 'moment-timezone/builds/moment-timezone-with-data-10-year-range.js'; // or .min.js

You can also import just the library without any preloaded data.

import moment from 'moment-timezone/moment-timezone.js'; // or .min.js
moment.tz.load(customData);

<script src="moment.js"></script>
<script src="moment-timezone-with-data.js"></script>

When using Moment Timezone in the browser, you will need to load the data as well as the library.

You can either use the prebuilt library and data files linked on the homepage or build a subset of the data yourself and load it.

moment().tz("America/Los_Angeles").format();

npm install moment-timezone

var moment = require('moment-timezone');
moment().tz("America/Los_Angeles").format();

Note: By default, webpack bundles all moment-timezone data (in moment-timezone 0.5.25, that’s over 900 KBs minified). To strip out unwanted data and bundle only the zone and date range data you need, add the moment-timezone-data-webpack-plugin package:

// webpack.config.js
const MomentTimezoneDataPlugin = require('moment-timezone-data-webpack-plugin');
const currentYear = new Date().getFullYear();

module.exports = {
    plugins: [
        // To include only specific zones, use the matchZones option
        new MomentTimezoneDataPlugin({
            matchZones: /^America/
        }),

        // To keep all zones but limit data to specific years, use the year range options
        new MomentTimezoneDataPlugin({
            startYear: currentYear - 5,
            endYear: currentYear + 5,
        }),
    ],
};

Alternatively, the pre-built bundles are also included in the npm package, and can be loaded directly. See the Node.js section for more details.

Also see the primary Moment.js Webpack documentation for an example of how to reduce Moment’s bundled locale data. Together these techniques can significantly reduce the final bundle size (by over 1 MB minified, or 85 KB minified + gzipped).

There are two interfaces for using time zones with Moment.js.

moment.tz(..., String) does parsing in given time zone

It takes all the same arguments as the moment constructor, but uses the last argument as a time zone identifier:

var a = moment.tz("2013-11-18 11:55", "Asia/Taipei");
var b = moment.tz("2013-11-18 11:55", "America/Toronto");

a.format(); // 2013-11-18T11:55:00+08:00
b.format(); // 2013-11-18T11:55:00-05:00

a.utc().format(); // 2013-11-18T03:55Z
b.utc().format(); // 2013-11-18T16:55Z

Note that created moments have different UTC time because these moments were created in different time zones.

moment().tz(String) does converting to provided time zone

var a = moment.utc("2013-11-18 11:55").tz("Asia/Taipei");
var b = moment.utc("2013-11-18 11:55").tz("America/Toronto");

a.format(); // 2013-11-18T19:55:00+08:00
b.format(); // 2013-11-18T06:55:00-05:00

a.utc().format(); // 2013-11-18T11:55Z
b.utc().format(); // 2013-11-18T11:55Z

In this example, you first create moment.utc("2013-11-18 11:55") object in UTC, and then change its timezone to specified. This also works if you create the object in your default timezone: moment("2013-11-18 11:55").

Note that created moments have equal UTC time because these moments were created in a default timezone.

moment.tz(..., String);

The moment.tz constructor takes all the same arguments as the moment constructor, but uses the last argument as a time zone identifier.

var a = moment.tz("2013-11-18 11:55", "America/Toronto");
var b = moment.tz("May 12th 2014 8PM", "MMM Do YYYY hA", "America/Toronto");
var c = moment.tz(1403454068850, "America/Toronto");
a.format(); // 2013-11-18T11:55:00-05:00
b.format(); // 2014-05-12T20:00:00-04:00
c.format(); // 2014-06-22T12:21:08-04:00

This constructor is DST aware, and will use the correct offset when parsing.

moment.tz("2013-12-01", "America/Los_Angeles").format(); // 2013-12-01T00:00:00-08:00
moment.tz("2013-06-01", "America/Los_Angeles").format(); // 2013-06-01T00:00:00-07:00

The offset is only taken into consideration when constructing with an array, string without offset, or object.

var arr = [2013, 5, 1],
    str = "2013-12-01",
    obj = { year : 2013, month : 5, day : 1 };

moment.tz(arr, "America/Los_Angeles").format(); // 2013-06-01T00:00:00-07:00
moment.tz(str, "America/Los_Angeles").format(); // 2013-12-01T00:00:00-08:00
moment.tz(obj, "America/Los_Angeles").format(); // 2013-06-01T00:00:00-07:00

moment.tz(arr, "America/New_York").format();    // 2013-06-01T00:00:00-04:00
moment.tz(str, "America/New_York").format();    // 2013-12-01T00:00:00-05:00
moment.tz(obj, "America/New_York").format();    // 2013-06-01T00:00:00-04:00

If the input string contains an offset, it is used instead for parsing. The parsed moment is then converted to the target zone.

var zone = "America/Los_Angeles";
moment.tz('2013-06-01T00:00:00',       zone).format(); // 2013-06-01T00:00:00-07:00
moment.tz('2013-06-01T00:00:00-04:00', zone).format(); // 2013-05-31T21:00:00-07:00
moment.tz('2013-06-01T00:00:00+00:00', zone).format(); // 2013-05-31T17:00:00-07:00

Unix timestamps and Date objects refer to specific points in time, thus it doesn't make sense to use the time zone offset when constructing. Using moment.tz(Number|Date, zone) is functionally equivalent to moment(Number|Date).tz(zone).

var timestamp = 1403454068850,
    date = new Date(timestamp);

moment.tz(timestamp, "America/Los_Angeles").format(); // 2014-06-22T09:21:08-07:00
moment(timestamp).tz("America/Los_Angeles").format(); // 2014-06-22T09:21:08-07:00

moment.tz(date, "America/Los_Angeles").format();      // 2014-06-22T09:21:08-07:00
moment(date).tz("America/Los_Angeles").format();      // 2014-06-22T09:21:08-07:00

Уou may specify a boolean right after format argument to use strict parsing. Strict parsing requires that the format and input match exactly, including delimeters.

moment.tz('It is 2012-05-25', 'YYYY-MM-DD', "America/Toronto").isValid();       // true 
moment.tz('It is 2012-05-25', 'YYYY-MM-DD', true, "America/Toronto").isValid(); // false
moment.tz('2012-05-25', 'YYYY-MM-DD', true, "America/Toronto").isValid();       // true
moment.tz('2012-05.25', 'YYYY-MM-DD', true, "America/Toronto").isValid();       // false

Due to daylight saving time, there is a possibility that a time either does not exist, or has existed twice.

Spring Forward

In the spring, at the start of DST, clocks move forward an hour. In reality though, it is not time that is moving, it is the offset moving.

Moving the offset forward gives the illusion that an hour has disappeared. As the clock ticks, you can see it move from 1:58 to 1:59 to 3:00. It is easier to see what is actually happening when you include the offset.

1:58 -5
1:59 -5
3:00 -4
3:01 -4

The result is that any time between 1:59:59 and 3:00:00 never actually happened. Moment Timezone accounts for this. If you try to parse a time that never existed, it will skip forward by the amount of the DST gap (usually 1 hour).

moment.tz("2012-03-11 01:59:59", "America/New_York").format() // 2012-03-11T01:59:59-05:00
moment.tz("2012-03-11 02:00:00", "America/New_York").format() // 2012-03-11T03:00:00-04:00
moment.tz("2012-03-11 02:59:59", "America/New_York").format() // 2012-03-11T03:59:59-04:00
moment.tz("2012-03-11 03:00:00", "America/New_York").format() // 2012-03-11T03:00:00-04:00

In this example, the two o'clock hour doesn't exist, so it is treated as equivalent to the three o'clock hour.

Fall Back

In the fall, at the end of DST, clocks move backward an hour. Again, time is not moving backwards, only the offset is. In this case, the illusion is that an hour repeats itself.

Again, it is easier to see what is actually happening when you include the offset.

1:58 -4
1:59 -4
1:00 -5
1:01 -5

Moment Timezone handles this by always using the earlier instance of a duplicated hour.

moment.tz("2012-11-04 00:59:59", "America/New_York"); // 2012-11-04T00:59:59-04:00
moment.tz("2012-11-04 01:00:00", "America/New_York"); // 2012-11-04T01:00:00-04:00
moment.tz("2012-11-04 01:59:59", "America/New_York"); // 2012-11-04T01:59:59-04:00
moment.tz("2012-11-04 02:00:00", "America/New_York"); // 2012-11-04T02:00:00-05:00

You won't be able to create a moment with the later instance of the duplicated hour unless you include the offset when parsing.

moment.tz("2012-11-04 01:00:00-04:00", "America/New_York"); // 2012-11-04T01:00:00-04:00
moment.tz("2012-11-04 01:00:00-05:00", "America/New_York"); // 2012-11-04T01:00:00-05:00

moment().tz(String);
moment().tz(String, Boolean);

The moment#tz mutator will change the time zone and update the offset.

moment("2013-11-18").tz("America/Toronto").format('Z'); // -05:00
moment("2013-11-18").tz("Europe/Berlin").format('Z');   // +01:00

This information is used consistently in other operations, like calculating the start of the day.

var m = moment.tz("2013-11-18 11:55", "America/Toronto");
m.format();                     // 2013-11-18T11:55:00-05:00
m.startOf("day").format();      // 2013-11-18T00:00:00-05:00
m.tz("Europe/Berlin").format(); // 2013-11-18T06:00:00+01:00
m.startOf("day").format();      // 2013-11-18T00:00:00+01:00

Without any argument, moment#tz returns:

• the time zone name assigned to the moment instance or
• undefined if a time zone has not been set.

var m = moment.tz("2013-11-18 11:55", "America/Toronto");
m.tz();  // America/Toronto
var m = moment.tz("2013-11-18 11:55");
m.tz() === undefined;  // true

On passing a second parameter as true, only the timezone (and offset) is updated, keeping the local time same. Consequently, it will now point to a different point in time if the offset has changed.

var m = moment.tz("2013-11-18 11:55", "America/Toronto");
m.format();                           // 2013-11-18T11:55:00-05:00
m.tz('Europe/Berlin', true).format()  // 2013-11-18T11:55:00+01:00

moment.tz(String).format("Z z"); // -08:00 PST
moment.tz(String).zoneAbbr();    // PST
moment.tz(String).zoneName();    // PST

In addition to including the +00:00 formatting information, Moment Timezone also includes information for the abbreviated time zone name.

moment.tz([2012, 0], 'America/New_York').format('z');    // EST
moment.tz([2012, 5], 'America/New_York').format('z');    // EDT
moment.tz([2012, 0], 'America/Los_Angeles').format('z'); // PST
moment.tz([2012, 5], 'America/Los_Angeles').format('z'); // PDT

Note that these abbreviations may change depending on the time zone offset. This helps to distinguish offsets between places that may or may not use DST.

// Denver observes DST
moment.tz([2012, 0], 'America/Denver').format('Z z');  // -07:00 MST
moment.tz([2012, 5], 'America/Denver').format('Z z');  // -06:00 MDT
// Phoenix does not observe DST
moment.tz([2012, 0], 'America/Phoenix').format('Z z'); // -07:00 MST
moment.tz([2012, 5], 'America/Phoenix').format('Z z'); // -07:00 MST

Note also that these abbreviations are not globally unique. Below, you can see that both United States Central Standard Time and China Standard Time have the same abbreviation.

moment.tz('2016-01-01', 'America/Chicago').format('z');    // CST
moment.tz('2016-01-01', 'Asia/Shanghai').format('z');      // CST

You can also use moment#zoneAbbr to get the zone abbreviation. This is what moment.js uses when formatting the z token.

moment.tz([2012, 0], 'America/New_York').zoneAbbr(); // EST
moment.tz([2012, 5], 'America/New_York').zoneAbbr(); // EDT

Moment.js also provides a hook for the long form time zone name. Because these strings are generally localized, Moment Timezone does not provide any long names for zones.

To provide long form names, you can override moment.fn.zoneName and use the zz token.

var abbrs = {
    EST : 'Eastern Standard Time',
    EDT : 'Eastern Daylight Time',
    CST : 'Central Standard Time',
    CDT : 'Central Daylight Time',
    MST : 'Mountain Standard Time',
    MDT : 'Mountain Daylight Time',
    PST : 'Pacific Standard Time',
    PDT : 'Pacific Daylight Time',
};

moment.fn.zoneName = function () {
    var abbr = this.zoneAbbr();
    return abbrs[abbr] || abbr;
};

moment.tz([2012, 0], 'America/New_York').format('zz');    // Eastern Standard Time
moment.tz([2012, 5], 'America/New_York').format('zz');    // Eastern Daylight Time
moment.tz([2012, 0], 'America/Los_Angeles').format('zz'); // Pacific Standard Time
moment.tz([2012, 5], 'America/Los_Angeles').format('zz'); // Pacific Daylight Time

Please note that the z formatting token will not always show the abbreviated time zone name, instead, will show the time offsets for each region.

moment.tz('America/Los_Angeles').format('z')  // "PDT"     (abbreviation)
moment.tz('Asia/Magadan').format('z')         // "+11"     (3-char offset)
moment.tz('Asia/Colombo').format('z')         // "+0530"   (5-char offset)

moment.tz.setDefault(String);

By default, moment objects are created in the local time zone. The local time zone is determined by your JS environment such as a browser or server like Node.js.

To change the default time zone, use moment.tz.setDefault with a valid time zone.

moment.tz.setDefault("America/New_York");

To reset the default time zone to local, use moment.tz.setDefault with no arguments.

moment.tz.setDefault();

This is a global setting (shared by all modules).

Subsequent calls to moment.tz.setDefault will not affect existing moment objects or their clones.

moment.tz.guess();
moment.tz.guess(Boolean);

Moment Timezone uses the Internationalization API (Intl.DateTimeFormat().resolvedOptions().timeZone) in supported browsers to determine the user's time zone.

On other browsers, time zone detection is rather tricky to get right, as there is little information provided by those browsers. For those, it will use Date#getTimezoneOffset and Date#toString on a handful of moments around the current year to gather as much information about the browser environment as possible. It then compares that information with all the time zone data loaded and returns the closest match. In case of ties, the time zone with the city with largest population is returned.

By default Moment Timezone caches the detected timezone. This means that subsequent calls to moment.tz.guess() will always return the same value.

You can call moment.tz.guess() with an optional boolean argument "ignoreCache". If set to true, the cache will be ignored and overwritten with the new value.

moment.tz.guess(); // America/Chicago
// suppose the client's timezone changes to Europe/Berlin
moment.tz.guess(); // America/Chicago
moment.tz.guess(true); // Europe/Berlin
moment.tz.guess(); // Europe/Berlin

moment.tz.names(); // String[]

To get a list of all available time zone names, use moment.tz.names.

moment.tz.names(); // ["Africa/Abidjan", "Africa/Accra", "Africa/Addis_Ababa", ...]

moment.tz.zonesForCountry(String); // String[]
moment.tz.zonesForCountry(String, Boolean);

To get a list of time zones for some country, use moment.tz.zonesForCountry().

moment.tz.zonesForCountry('US');

By default this method returns zone names sorted alphabetically:

["America/Adak", "America/Anchorage", ... "Pacific/Honolulu"]

To get also offsets, pass true as 2nd parameter:

moment.tz.zonesForCountry('CN', true);

it returns array of objects with name and offset:

[
   { name: "Asia/Shanghai", offset: -480 },
   { name: "Asia/Urumqi", offset: -360 }
]

It's useful if you need to sort time zones by offset.

All country codes can be retrieved using method moment.tz.countries()

In order to match a timestamp to an offset, Moment Timezone uses a Zone object.

Though you shouldn't even need to use it, this object's constructor is available on the moment.tz.Zone namespace.

This object has 5 properties.

{
    name       : 'America/Los_Angeles',          // the unique identifier
    abbrs      : ['PDT', 'PST'],                 // the abbreviations
    untils     : [1414918800000, 1425808800000], // the timestamps in milliseconds
    offsets    : [420, 480],                     // the offsets in minutes
    population : 15000000                        // a rough population count for the largest city in this zone
}

zone.name; // America/Los_Angeles

The uniquely identifying name of the time zone. See the IANA Time Zone database naming guidelines for more details about the naming convention.

Note that the guidelines also say that these zone identifiers shouldn't be displayed directly to end users:

Inexperienced users are not expected to select these names unaided. Distributors should provide documentation and/or a simple selection interface that explains each name via a map or via descriptive text like "Czech Republic" instead of the timezone name "Europe/Prague".

Providing a full list of translated zone names for every locale is outside the scope of Moment Timezone. The Unicode CLDR project contains locale-aware mappings for this purpose.

zone.abbr(timestamp); // PST

Get the abbreviation for a given timestamp (in milliseconds) from a Zone.

moment.tz.zone('America/Los_Angeles').abbr(1403465838805); // PDT
moment.tz.zone('America/Los_Angeles').abbr(1388563200000); // PST

zone.utcOffset(timestamp); // 480

Get the offset for a given timestamp (in milliseconds) from a Zone.

moment.tz.zone('America/Los_Angeles').utcOffset(1403465838805); // 420
moment.tz.zone('America/Los_Angeles').utcOffset(1388563200000); // 480

POSIX compatibility requires that the offsets are inverted. Therefore, Etc/GMT-X will have an offset of +X and Etc/GMT+X will have an offset of -X. This is a result of IANA's Time Zone Database and not an arbitrary choice by Moment.js. Thus, using locality based identifiers is preferred over fixed-offset identifiers.

This is also described on the Wikipedia entry for the database:

The special area of "Etc" is used for some administrative zones, particularly for "Etc/UTC" which represents Coordinated Universal Time. In order to conform with the POSIX style, those zone names beginning with "Etc/GMT" have their sign reversed from the standard ISO 8601 convention. In the "Etc" area, zones west of GMT have a positive sign and those east have a negative sign in their name (e.g "Etc/GMT-14" is 14 hours ahead of GMT).

For example, using the Europe/Madrid identifier gives a different result from Etc/GMT+1.

moment().tz('Etc/GMT+1').format('YYYY-MM-DD HH:mm ZZ');
// '2014-12-18 11:22 -0100'
moment().tz('Europe/Madrid').format('YYYY-MM-DD HH:mm ZZ');
// '2014-12-18 13:22 +0100'

zone.parse(timestamp); // 480

Parse an offset for a timestamp constructed from Date.UTC in that zone.

This is what Moment Timezone uses to parse input into a time zone. The process is conceptually similar to the following.

Assume we want to find the exact moment of March 19 2014 8:30 am in New York. Because the offset varies between -04:00 and -05:00 in New York, we don't know what the offset was on March 19th.

Instead, we create a timestamp in UTC and pass that to zone.parse, which will return the offset at that time.

var zone = moment.tz.zone('America/New_York');
zone.parse(Date.UTC(2012, 2, 19, 8, 30)); // 240

This is the code that handles the cases referenced in the Parsing Ambiguities section above.

var zone = moment.tz.zone('America/New_York');
zone.parse(Date.UTC(2012, 2, 11, 1, 59)); // 300
zone.parse(Date.UTC(2012, 2, 11, 2, 0)); // 240

Moment Timezone uses two data formats. An unpacked version for calculations and a packed version for minified transport.

The unpacked format looks exactly like the zone object.

The data below is for Los Angeles between 2014 and 2018.

{
    name       : 'America/Los_Angeles',
    abbrs      : ['PST', 'PDT','PST', 'PDT', 'PST', 'PDT', 'PST', 'PDT', 'PST', 'PDT', 'PST'],
    untils     : [1394359200000, 1414918800000, 1425808800000, 1446368400000, 1457863200000, 1478422800000, 1489312800000, 1509872400000, 1520762400000, 1541322000000, null],
    offsets    : [480, 420, 480, 420, 480, 420, 480, 420, 480, 420, 480],
    population : 15000000,
    countries  : ['US']
}

The lengths of abbrs, untils, offsets are all the same. The offset and abbr at any index are only active while the timestamp is less than the until at that index.

An easy way to read this aloud is "between untils[n-1] and untils[n], the abbr should be abbrs[n] and the offset should be offsets[n]".

Note that untils are measured in milliseconds and offsets are measured in minutes.

The packed format represents an unpacked zone in a single string.

The data below is for Los Angeles between 2014 and 2018. More time zones can be seen in the packed source file.

'America/Los_Angeles|PST PDT|80 70|01010101010|1Lzm0 1zb0 Op0 1zb0 Rd0 1zb0 Op0 1zb0 Op0 1zb0|15e6'

In order to save as many bytes as possible, we used a very compact format to store the data.

The data is split into 6 sections separated by pipes.

Name: The canonical name of the time zone.

Abbr Map: A space separated list of all the abbreviations ever used in this time zone.

Offset Map: A space separated list of all the offsets ever used in this time zone in minutes in base 60.

Abbr/Offset Index: A tightly packed array of indices into the offset and abbr maps. These are also in base 60.

Timestamp Diffs: This is where the timestamps are stored.

Because we are dealing with a sorted list of timestamps, we just store the diff from the last timestamps rather than storing the full timestamps.

The first item in the array is a unix timestamp in minutes. All items after the first item are numbers of minutes to be added to the previous value during unpacking. All items are stored in base 60.

As you may have seen from the example above, the timestamp diffs tend to duplicate the same values from year to year. These duplications allow gzip to compress the data even further than if we used full timestamps.

Population: The rough population size of the city that the zone is named after.

This is not in base 60, but instead uses scientific exponential notation. For example, a value of 15e6 means 15 * 10⁶ (that's 15 with 6 zeros after it) and therefore represents the number 15,000,000.

The value is only used to compare nearly-identical zones when using the guess feature, so it doesn't need to be precise.

Note that this value might be empty for some zones.

Base 60?

You may be wondering why base 60 is used. Base 62 is a fairly common tool for ascii data compression, using a-z to represent 10-35 and A-Z to represent 36-61.

While it may have saved a few bytes to use base 62, much of the data in Moment Timezone maps nicely to multiples of 60.

There are 60 minutes in an hour and 60 seconds in a minute. 3 hours is 30 minutes in base 60 and 300 seconds in base 60 instead of 180 and 10800 in base 10 or 2U and 2Oc in base 62.

In order to reduce duplication, the Moment Timezone data packer will create links out of two zones that share data that is exactly the same.

This data is the two zone names separated by a pipe.

moment.tz.add('America/Los_Angeles|PST PDT|80 70|01010101010|1Lzm0 1zb0 Op0 1zb0 Rd0 1zb0 Op0 1zb0 Op0 1zb0');
moment.tz.link('America/Los_Angeles|US/Pacific');
moment.tz("2013-12-01", "America/Los_Angeles").format(); // 2013-12-01T00:00:00-08:00
moment.tz("2013-12-01", "US/Pacific").format();          // 2013-12-01T00:00:00-08:00

Once the data has been packed and transported to the client, it must be added to Moment Timezone.

This happens automatically in Node.js and the pre-built bundles. If you're using a different loading method you might need to load the data yourself.

moment.tz.add(PackedZoneString)
moment.tz.add(PackedZoneString[])

To add zone data to Moment Timezone, use moment.tz.add.

moment.tz.add('America/Los_Angeles|PST PDT|80 70|0101|1Lzm0 1zb0 Op0');

To add more than one zone, pass an array of packed data.

moment.tz.add([
    'America/Los_Angeles|PST PDT|80 70|0101|1Lzm0 1zb0 Op0',
    'America/New_York|EST EDT|50 40|0101|1Lz50 1zb0 Op0'
]);

Note: The above zone data is sample data and is not up to date. Reference the moment-timezone source for up to date data.

moment.tz.link(PackedLinkString)
moment.tz.link(PackedLinkString[])

To link two zone names to the same data, use moment.tz.link.

The strings passed in should be in the link format: the two zone names separated by a pipe.

moment.tz.link('America/Los_Angeles|US/Pacific');

To add more than one link at a time, pass an array of link strings.

moment.tz.link([
    'America/Los_Angeles|US/Pacific',
    'America/New_York|US/Eastern'
]);

moment.tz.load({
    zones : [],
    links : [],
    version : '2014e'
});

The data for Moment Timezone comes from the IANA Time Zone Database. New versions are released periodically as time zone laws change in various countries.

The versions are named after the year and an incrementing letter. 2014a 2014b 2014c...

In order to keep versions together, Moment Timezone has a bundled object format as well.

{
    version : '2014e',
    zones : [
        'America/Los_Angeles|PST PDT|80 70|0101|1Lzm0 1zb0 Op0',
        'America/New_York|EST EDT|50 40|0101|1Lz50 1zb0 Op0'
    ],
    links : [
        'America/Los_Angeles|US/Pacific',
        'America/New_York|US/Eastern'
    ]
}

To load a bundle into Moment Timezone, use moment.tz.load.

moment.tz.load({
    version : '2014e',
    zones : [...],
    links : [...]
})

moment.tz.zone(name); // Zone or null

To check if a zone exists, use moment.tz.zone. It will return the Zone if it was loaded and null if it was not loaded.

moment.tz.zone("UnloadedZone"); // null
moment.tz.add("UnloadedZone|UZ|0|0|");
moment.tz.zone("UnloadedZone"); // Zone { name : "UnloadedZone", ...}

moment.tz.names(); // String[]

To get a list of all available time zone names, use moment.tz.names.

moment.tz.names(); // ["Africa/Abidjan", "Africa/Accra", "Africa/Addis_Ababa", ...]

Because of the complexity of the packed and unpacked data formats, Moment Timezone has some heavily tested utility functions for working with the data.

Methods for unpacking data are included with the core library, as they are needed in order to use the library.

Methods for packing and subsetting the data are included in an additional moment-timezone-utils.js file. This file adds some more methods to the moment.tz namespace.

// in moment-timezone.js
moment.tz.unpack
moment.tz.unpackBase60
// in moment-timezone-utils.js
moment.tz.pack
moment.tz.packBase60
moment.tz.createLinks
moment.tz.filterYears
moment.tz.filterLinkPack

moment.tz.pack(UnpackedObject); // PackedString

This converts data in the unpacked format to the packed format.

var unpacked = {
    name       : 'Indian/Mauritius',
    abbrs      : ['LMT', 'MUT', 'MUST', 'MUT', 'MUST', 'MUT'],
    offsets    : [-230, -240, -300, -240, -300, -240],
    untils     : [-1988164200000, 403041600000, 417034800000, 1224972000000, 1238274000000, null],
    population : 150000
};
moment.tz.pack(unpacked); // "Indian/Mauritius|LMT MUT MUST|-3O -40 -50|012121|-2xorO 34unO 14L0 12kr0 11z0|15e4"

moment.tz.unpack(PackedString); // UnpackedObject

This converts data in the packed format to the unpacked format.

var packed = "Indian/Mauritius|LMT MUT MUST|-3O -40 -50|012121|-2xorO 34unO 14L0 12kr0 11z0|15e4";

moment.tz.unpack(packed);
// {
//     name       : 'Indian/Mauritius',
//     abbrs      : ['LMT', 'MUT', 'MUST', 'MUT', 'MUST', 'MUT'],
//     offsets    : [-230, -240, -300, -240, -300, -240],
//     untils     : [-1988164200000, 403041600000, 417034800000, 1224972000000, 1238274000000, null],
//     population : 150000
// };

moment.tz.packBase60(Number); // Base60String

Convert a base 10 number to a base 60 string.

moment.tz.packBase60(9);    // 9
moment.tz.packBase60(10);   // a
moment.tz.packBase60(59);   // X
moment.tz.packBase60(1337); // mh

Much like Number.prototype.toFixed, moment.tz.packBase60 accepts a second argument for the number of digits of precision.

moment.tz.packBase60(1.1667,   1); // 1.a
moment.tz.packBase60(20.12345, 3); // k.7op
moment.tz.packBase60(59,       1); // X

A solitary 0 before the decimal point is dropped.

moment.tz.packBase60(1.1667, 1); // 1.a
moment.tz.packBase60(0.1667, 1); // .a

Trailing zeroes after the decimal point are dropped.

moment.tz.packBase60(1/6, 1); // .a
moment.tz.packBase60(1/6, 5); // .a
moment.tz.packBase60(59, 5);  // X

moment.tz.unpackBase60(Base60String); // Number

Convert a base 60 string to a base 10 number.

moment.tz.unpackBase60('9');     // 9
moment.tz.unpackBase60('a');     // 10
moment.tz.unpackBase60('X');     // 59
moment.tz.unpackBase60('mh');    // 1337
moment.tz.unpackBase60('1.9');   // 1.15
moment.tz.unpackBase60('k.7op'); // 20.123449074074074

moment.tz.createLinks(UnpackedBundle); // UnpackedBundle

In order to reduce duplication, we can create links out of two zones that share data.

var unlinked = {
    zones : [
        {name:"Zone/One",abbrs:["OST","ODT"],offsets:[60,120],untils:[403041600000,417034800000]},
        {name:"Zone/Two",abbrs:["OST","ODT"],offsets:[60,120],untils:[403041600000,417034800000]}
    ],
    links : [],
    version : "2014x-doc-example"
};

moment.tz.createLinks(unlinked);

{
    zones : [
        {name:"Zone/One",abbrs:["OST","ODT"],offsets:[60,120],untils:[403041600000,417034800000]}
    ],
    links : ["Zone/One|Zone/Two"],
    version : "2014x-doc-example"
}

This is especially useful when combined with moment.tz.filterYears, as older rules that would have differentiated two Zones may not be in the filtered year range, allowing them to be linked to save space.

moment.tz.filterYears(UnpackedZone, Number, Number); // UnpackedZone

By default, Moment Timezone includes all the data from the IANA Time Zone Database. This includes data from at least 1900 to 2038. Releases from version 0.5.37 onward include even more data, beyond the year 2400. The data for all these years may not be necessary for your use case.

moment.tz.filterYears can be used to filter out data for years outside a certain range.

var all    = { name : "America/Los_Angeles", abbrs : [...], offsets : [...] untils : [...]};
var subset = moment.tz.filterYears(all, 2012, 2016);
all.untils.length;    // 186
subset.untils.length; // 11

If only one year is passed, it will be used for the start and end year.

var all    = { name : "America/Los_Angeles", abbrs : [...], offsets : [...] untils : [...]};
var subset = moment.tz.filterYears(all, 2012);
all.untils.length;    // 186
subset.untils.length; // 3

Alternatively, one of the smaller pre-built bundles available on the homepage might already fit your needs.

moment.tz.filterLinkPack(UnpackedBundle, Number, Number); // PackedBundle

The packing, link creation, and subsetting of years are all tools for compressing data to be transported to the client.

The moment.tz.filterLinkPack method combines all these into one simple interface. Pass in an unpacked bundle, start year, and end year and get a filtered, linked, packed bundle back.

This is what is being used to compress the output for the bundled data + library files on the homepage.