Comment 3 for bug 1617008

I’ve had a look at the code for jquery-localize¹ and I can confirm that it doesn’t handle language codes with more than two letters (i.e. it assumes ISO 639-1 codes).
However navigator.language may return 3-letter codes².
In its current implementation, jquery-localize would trim "ast" to "as", thus loading translations for Assamese instead of Asturian.
What we really need to do here is fix jquery-localize instead of working around the issue.

The issue with Chinese is different³: jquery-localize tries to load a generic language file (zh.json) first, and if it fails to do so it won’t load the culture-specific one (zh-CN.json). Again this should be fixed in jquery-localize.

Finally, it appears jquery-localize doesn’t handle language variant codes at all (e.g. ca-ES-valencia), even though we might have specific translations for those (launchpad would export <email address hidden>).

¹ https://github.com/coderifous/jquery-localize/blob/master/dist/jquery.localize.js
² https://developer.mozilla.org/en-US/docs/Web/API/NavigatorLanguage/language
³ https://github.com/coderifous/jquery-localize/issues/47