# The String toLocaleUpperCase() method

> Learn how the JavaScript toLocaleUpperCase() method returns an uppercase string using locale-specific case mappings, handy for languages like Turkish.

Author: [Flavio Copes](https://flaviocopes.com/about/) | Published: 2019-03-05 | Topics: [JavaScript](https://flaviocopes.com/tags/js/) | Canonical: https://flaviocopes.com/javascript-string-tolocaleuppercase/

Returns a new string with the uppercase transformation of the original string, according to the locale case mappings.

The first parameter represents the locale, but it's optional (and if omitted, the current locale is used):

```js
'Testing'.toLocaleUpperCase() //'TESTING'
'Testing'.toLocaleUpperCase('it') //'TESTING'
'Testing'.toLocaleUpperCase('tr') //'TESTİNG'
```

Similar to the [`toUpperCase()`](https://flaviocopes.com/javascript-string-touppercase/) method, except that does not take locales into consideration.