There is another 'modern' language that does utf8 right and has done it right for a long time. I know it's mostly fallen out of favour, but we're still out here: Perl.
$ perl -wle 'use utf8; print length("");'
1
Without use utf8:
$ perl -wle 'print length("");'
3
It's funny: after Perl fell out of favour, is when it got all its best stuff. It's still my preferred language for just about everything.