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Get-User-Locale

A function that returns user's locale as an IETF language tag, based on all available sources.

tl;dr

- Install by executing npm install get-user-locale or yarn add get-user-locale.
- Import by adding import getUserLocale from 'get-user-locale'.
- Do stuff with it!
``ts
const userLocale = getUserLocale();
`

User guide

$3

A function that returns user's preferred locale as an IETF language tag, based on all available sources.

#### Sample usage

`ts
import getUserLocale from 'get-user-locale';

getUserLocale(); // 'de-DE'
`

or

`ts
import { getUserLocale } from 'get-user-locale';

getUserLocale(); // 'de-DE'
`

##### Options

getUserLocale() may be called with an optional options argument.

options object may contain the following properties:

| Property | Description | Default value |
| ------------------- | ----------------------------------- | ------------- |
| fallbackLocale | A locale to use as a fallback. | en-US |
| useFallbackLocale | Whether to use the fallback locale. | true |

$3

A function that returns an array of user's preferred locales as an IETF language tags, based on all available sources.

#### Sample usage

`ts
import { getUserLocales } from 'get-user-locale';

getUserLocales(); // ['de-DE', 'de', 'en-US', 'en']
`

##### Options

getUserLocales() may be called with an optional options argument.

options object may contain the following properties:

| Property | Description | Default value |
| ------------------- | ----------------------------------- | ------------- |
| fallbackLocale | A locale to use as a fallback. | en-US |
| useFallbackLocale | Whether to use the fallback locale. | true |

Technical details

There are a few ways of determining user's locale:

- window.navigator.languages
- window.navigator.language

…languages is an array of strings, …language is a string. Some browsers return mixed-case IETF language tags (e.g. de-DE), while others return lowercase ones (e.g. de-de). Finally, non-browser environments will not return anything, so you need a fallback.

Get-User-Locale does the following:

- Combines all of them into one sane set of locales - in that particular order,
- Dedupes them,
- Fixes invalid, lowercased IETF language tags (so that the part after - is always uppercased),
- Adds a fallback to en-US`, so if all else fails, you will get a result that won't crash your app.

License

The MIT License.

Author

Wojciech Maj