Awesome Open Source
Awesome Open Source


Provides localization services for Electron and the browser. Respects the OS date and time format configuration.


npm i@microsoft/globe


import { TimeStringFormat, DateTimeFormatOptions, DateTimeFormatter } from 'globe';

// Instantiate the formatter
const dateTimeFormatter = new DateTimeFormatter(locale: string | ILocaleInfo);

locale is either a locale string (e.g.: en-US) or ILocaleInfo instance:

type ILocaleInfo = {
  // Supported platform
  platform: 'windows' | 'macos';

  // OS date & time format settings (see below for OS support)
  regionalFormat: string; // e.g.: 'en-US'
  shortDate: string; // e.g.: 'dd/MM/y'
  longDate: string; // e.g.: 'd MMMM y'
  fullDate: string; // e.g.: 'EEEE d MMMM y'
  shortTime: string; // e.g.: 'HH:mm'

To format a date and time value:

 * Localize the date/time
 * @param date The date/time to localize
 * @param format The format to be used for the localization
 * @returns The localized date/time string
function formatDateTime(date: number | Date, format: DateTimeFormatOptions) {
  return dateTimeFormatter.formatDateTime(date, format);

The function throws in case an unexpected OS date and time format string is provided! Most likely this will happen if you feed it the OS strings verbatim and the OS is configured with a custom date/time format string. If you don't desire this behavior, you can choose your own fallback (and telemetry) by wrapping the call to Globe and redoing it without OS-honoring support in case it fails with the Unexpected format string error.

OS Support

Globe is able to honor OS system date and time formatting settings, but it does not do OS detection and date and time settings querying out of the box as these features depend on the context you're using Globe in.

If you want to take an advantage of this feature, we recommend you follow this pattern:

  • Make window.getLocaleInfoAsync available (return Promise<ILocaleInfo>)
  • Cache the result of that function and provide it in the DateTimeFormatter constructor
  • Use the exported getLocaleInfoAsync alias function if you prefer, which wraps the window.getLocaleInfoAsync function for you:
import { getLocaleInfoAsync } from '@microsoft/globe';
// Provide the supported platform name and obtain the OS locale settings
const localeInfo = await getLocaleInfoAsync(/* 'windows` | 'macos' */);
new DateTimeFormatter(localeInfo);


The values provided can be found in Date & Time this way:

  • Click on the date and time in the taskbar
  • Click on Adjust date and time
  • Click on Region & language (here you see the values formatted)
  • Click on Advanced
  • Check the values of short date, long date and short time


  • Click on the date and time in the menubar
  • Click on Open date and time preferences
  • Click on Date and time
  • Click on Oppen language and region
  • Click on Advanced
  • Click on Dates
  • Check the values of short and long

  • Click on Times
  • Check the value of

MacOS format patterns reference


npm install
npm run build


Build the package first: npm run build.

npm test

There is a GitHub Actions workflow which runs the tests on every push to any branch.

GitHub Release Publishing

GitHub Releases are made manually by @TomasHubelbauer at the moment.

NPM Release Publishing

Don't forget to build prior to cutting a release!

# --tag=next pro pre-release (also include a pre-release tag in the version code)
npm publish [--tag=next]
# @microsoft/globe

Install the pre-release package using: npm i @microsoft/[email protected]

NPM Releases are made manually by @TomasHubelbauer at the moment.

Release Notes

4.1.3 2021-08-09

Attempting to fix VDI issues on Electron

4.1.2 2021-03-31

Fixed 12 hours format for Windows

4.1.1 2021-02-18

Use for loops in an attempt to reduce memory consumption

4.1.0 2021-02-03

Use reducers in an attempt to reduce memory consumption (eliminate anonymous functions) Better checks for cases where time zone is not provided by default

4.0.0 2020-11-10

Use hourCycle for mac as it is supported in Electron 8

3.5.0 2020-10-29

Mac full date format

3.4.0 2020-10-29

Support quotes in format Support K and k tokens for mac

3.3.0 2020-10-057


3.2.0 2020-10-05


3.1.0 2020-09-08

Add getLocaleInfoAsync to module export

3.0.1 2020-09-04

Improve error logging for unknown formats

3.0.0 2020-07-22

Avoid depending on Intl.DateTimeFormatParts which is not available in es5

2.8.1 2020-07-20

SafeDateTimeFormat with fallback to UTC if timezone is not detected or provided Use 0 instead of 24 for H and HH tokens

2.8.0 2020-06-29


2.7.4 2020-06-29

Do not use for...of because of perf impact.

2.7.3 2020-06-16

Improved performance, by adding more caching.

2.7.2 2020-05-25

Fixed a bug in Windows AM/PM token detection in the OS formatting string. Instead for looking for either t or tt, Globe was only looking for tt.

2.7.1 2020-05-19

Fixed typo in seconds in long date and time format.

2.7.0 2020-05-19

Added formatting rules for:

  • Long date and time
  • Long weekday and long time
  • Long weekday and short time
  • Short weekday and long time
  • Short weekday and short time

2.6.2 2020-05-14

Fixed an issue where Windows OS format string was treated as if it was a macOS format string.

2.6.1 2020-05-14

We've added preliminary handling for AM/PM (day period) format which supports the HOUR_ONLY option when using the OS date and time format strings. The supported OSs (macOS and Windows) do not expose a dedicated format string for an hour-only scenario, so we detect whether the OS format string for short date includes the AM/PM format string token and constuct a makeshift HOUR_ONLY format string for that case which either also includes AM/PM or doesn't depending on if the original short time format string did.

2.6.0 2020-05-04

We've switched to a single-level cache between the pair made up by the locale and the format options stringified and the DateTimeFormat Intl instance.

Previously the cache was two-level, a map for the locale (string) and a weak map for the format options (object), which had the same performance, but was more complex and needlessly so, because JSON.stringify is so fast being native code, the overhead has actually decreased when using it for the cache key.

The access pattern of Globe is now such that the first call to formatDate given an format options object (or undefined) takes about 20ms, which is the cost of initializing and caching the Intl.DateTimeFormat instance and subsequent calls are practically equivalent in speed to raw Intl, meaning they take <1ms.

2.5.0 2020-05-04

Add missing key coercion which caused the locale+format cache to have no effect in case no format was provided.

2.4.0 2020-05-04

Caching internal Intl.DateTimeFormat instances keyed by the given locale and format object.

2.3.0 2020-03-09

Added HOUR_ONLY pattern.

2.2.0 2020-03-05

Added few more date time formatting patterns, like Medium and Full dates and times.

2.1.0 2020-02-24

Refactored the DateTimeFormatter constructor to accept either a locale string or an instance of ILocaleInfo and added information and support for obtaining ILocaleInfo through OS settings.

1.0.2 2020-02-11

Release a version with the release notes in the readme.

1.0.1 2020-02-11

  • Fixed a typo in the file name in the module field of package.json
  • Fixed installation instructions to use the current scope - @microsoft
  • Fixed the usage sample and clean up the readme a bit

1.0.0 2020-02-06

Initial release of the code pulled out of a larger codebase for public consumption.


Set up Jest to run with TypeScript and TSDX and in watch mode

Right now the tests are too rudimentary and are in JavaScript. Doing this will make it easier, faster and less error-prone to test the library.

Set up automated GitHub and NPM releases

We don't cut releases too often, but this will still be useful to make the release process reproducible, reliable and consistent.

Add more docs, especially around formatting based on OS date time settings

We're in a process of redesigning the OS-formatting portion of this library and will publish a design documentation first and an implementation PR second when we're ready to invest more resources into improving this.

Throw a custom error when hitting an unexpected OS date and time format string

This will be useful when attempting to catch this exact error. Right now we only throw this error so barring programming errors any error that can possibly be caught is this one, but it will be better to provide prototype equality (e instanceof OSDateTimeError) to be able to catch more selectively and confidently.


Contributions are welcome (see the CONTRIBUTING file), though please keep in mind the work-in-progress proof-of-concept state. Might make sense to just observe/discuss until the thing gets stable and well-documented.


This project is licensed under the MIT License, see the LICENSE file for details.

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