The internal string encoding of a programming language doesn't matter as long as it supports UTF-8 at the boundaries. E.g. the text encoding standard on the web

The internal string encoding of a programming language doesn't matter as long as it supports UTF-8 at the boundaries. E.g. the text encoding standard on the web is clearly UTF-8, even though JS strings may be internally stored as UTF-16 (or any other encoding). Same on macOS/iOS btw: AFAIK NSString is internally UTF-16, but I've never seen a UTF-16 text file on macOS, it's all UTF-8 (unless the file originated on Windows of course).