Right but it's pretty clear that UTF-8 is the better, de facto choice. JS strings only use UTF-16 for historic reasons. If designed today they would definitely use UTF-8.
Since some languages use UTF-8 and some use UTF-16 you're always going to have some languages doing conversions so it makes sense just to pick the best option surely?
Since some languages use UTF-8 and some use UTF-16 you're always going to have some languages doing conversions so it makes sense just to pick the best option surely?