use Intl.Locale for langneg

[ImUrX]

Requires fixing some test errors

[ImUrX]

Yes as you can see I handle the private-usage part by just reading the last subtag (because its always the last one), what should I do?

[ImUrX]

I also personally ended up using a ponyfill of the Intl.LocaleMatcher standard proposal in my code.

[eemeli]

Yes as you can see I handle the private-usage part by just reading the last subtag (because its always the last one), what should I do?

I see that. Hmmm. Could you make use of the normalization done in the baseName? As in, split it by - and compare the parts for each locale? That might allow for the implementation change to be considered a relaxation of the variant regexp.