What ISO standard for language codes does react-i18next / i18n follow?

Question

What ISO standard for language codes does react-i18next / i18n follow?

I've been searching around and my best guess is ISO 3166-1, but I can't find any concrete documentation.

Can anyone answer this?

Answer 1

I don't think there is a standard for language codes in react-i18next. I have seen people using 'arab' or 'dev' ( like in this documentation ) as language codes. But yeah, there is probably no official documentation about this.

Answer 2

Best seems to be if using the iana language tags format:

• en
• en-US
• en-GB

https://www.i18next.com/how-to/faq#how-should-the-language-codes-be-formatted