I think it's very different: "use strict" is strictly local (function or script scoped), "use utf-8" would require the entire JavaScript context to cooperate. I

I think it's very different: "use strict" is strictly local (function or script scoped), "use utf-8" would require the entire JavaScript context to cooperate. It means you can't safely use a library that expects UTF-16 in an app with "use utf-8". E.g. you can't include Google Analytics in your "use utf-8" web page.