> In a .js file, each character is UTF-16 (2 bytes).

What? I'd like to challenge this. The in-memory representation of a character may be UTF-16, but the file on disk can be UTF-8. Also UTF-16 doesn't mean "2 bytes per character": https://stackoverflow.com/a/27794229

The file https://github.com/AZHenley/coord2state/blob/main/dist/coord... doesn't use anything other than the 1-byte ASCII characters.