iLib
The most comprehensive library of Javascript i18n classes available
... locales.
Everything in iLib is written in pure JS with minimal platform dependencies, so it works the same way in many different environments and browsers, from Chrome to Opera to node to Qt/QML. Over 17K unit tests help to guarantee this.
ILib is also the library of choice for enyo apps on webOS which ships on over 10 million LG SmartTVs in over 135 countries. Give it a try and see if it can work for your app too!