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string.toLocaleLowerCase

The toLocaleLowerCase() method returns the calling string value converted to lower case, according to any locale-specific case mappings.

Syntax

str.toLocaleLowerCase()
str.toLocaleLowerCase(locale) 
str.toLocaleLowerCase([locale, locale, ...])

Parameters

locale Optional
The locale parameter indicates the locale to be used to convert to lower case according to any locale-specific case mappings. If multiple locales are given in an Array, the best available locale is used. The default locale is the host environment’s current locale.

Return value

A new string representing the calling string converted to lower case, according to any locale-specific case mappings.

Exceptions

  • A RangeError ("invalid language tag: xx_yy") is thrown if a locale argument isn't a valid language tag.
  • A TypeError ("invalid element in locales argument") is thrown if an array element isn't of type string.

Description

The toLocaleLowerCase() method returns the value of the string converted to lower case according to any locale-specific case mappings. toLocaleLowerCase() does not affect the value of the string itself. In most cases, this will produce the same result as toLowerCase(), but for some locales, such as Turkish, whose case mappings do not follow the default case mappings in Unicode, there may be a different result.

Examples

Using toLocaleLowerCase()

'ALPHABET'.toLocaleLowerCase(); // 'alphabet'

'\u0130'.toLocaleLowerCase('tr') === 'i';    // true
'\u0130'.toLocaleLowerCase('en-US') === 'i'; // false

let locales = ['tr', 'TR', 'tr-TR', 'tr-u-co-search', 'tr-x-turkish'];
'\u0130'.toLocaleLowerCase(locales) === 'i'; // true

Specifications

Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
toLocaleLowerCase 1 12 1 5.5 4 1.3
locale 58 12 55 6 45 10
Mobile
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
toLocaleLowerCase 1 18 4 10.1 1 1.0
locale 58 58 55 43 10 7.0
Server
Node.js
toLocaleLowerCase 0.1.100
locale 13.0.0
13.0.0
0.12
Before version 13.0.0, only the locale data for en-US is available by default. When other locales are specified, the function silently falls back to en-US. To make full ICU (locale) data available for versions prior to 13, see Node.js documentation on the --with-intl option and how to provide the data.

See also

© 2005–2018 Mozilla Developer Network and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://wiki.developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/toLocaleLowerCase