Intl API now uses browser locale by default on all platforms

Published: | Categories: JavaScript


Firefox for macOS, Linux and Android were previously using the operating system’s locale setting for the ECMAScript Internationalization API if no locale is specified by the programmer. Firefox 55 and later will rather use the browser locale as the default value on not only Windows but all platforms.

The affected object and methods include:

This may lead to a date format change for some Firefox users. For example, the browser locale is en-US while the platform uses en-CA, the return value of the toLocaleDateString method would be 6/20/2017 instead of 2017-06-20.

Web developers may want to specify the optional locales argument for the API, probably using the current page’s locale, to achieve consistent results.