What encoding is expected for Node.js source code?

I’ve done some Google searches, but I get results related to encoding strings or files.

Can I write my Node.js JavaScript source code in UTF-8? Can I use non-ASCII characters in comments, strings, or as variable names?

ECMA-262 seems to require UTF-16 encoding, but Node.js won’t run a UTF-16 encoded .js file. It will, however run UTF-8 source and correctly interpret non-ASCII characters.

So is this by design or by “accident”? Is it specified somewhere that UTF-8 source code is supported?

javascript
node.js
unicode

Reference: http://mathiasbynens.be/notes/javascript-identifiers

UTF-8 characters are valid javascript variable names. Go ahead and encode UTF-8.