- Support ISO-8859-1 encoding (true ISO-8859-1 encoding, not Windows-1252) in addition to UTF-8, for all of the functions that can read text from files and write text to files, to avoid having to implement it by yourself one byte at a time. This is useful when you want text which is mostly ASCII, but which may contain extended characters that aren't Unicode. (There is no need to support any other character sets or encodings, though.)
- Document the C API better. Currently, the documentation isn't very good.
- Implement WTF-8 (if it isn't already), so that arbitrary JavaScript strings (which are strings of 16-bit characters) can be represented as UTF-8 without losing data. Often the text will be ASCII anyways, and you will want to use ordinary C strings,
- Add a API function to read/write strings of 16-bit characters. (This is probably unnecessary for property names, although it is helpful for strings.)
- Add an option to disable use of Unicode tables, in case your program does not use them. (UTF-8, String.prototype.codePointAt, etc would still work regardless, since they don't need Unicode tables to work. However, it would prevent Unicode properties from being used in regular expressions, remove String.prototype.normalize, and case conversion would be limited to ASCII (or perhaps ISO-8859-1) only.)
Additional optional extensions may be wanted, even if not enabled or even included in the executable by default (due to complexity), such as:
- PCRE.
- Option to disable automatic semicolon insertion.
- A "goto" command; you cannot jump into blocks, past declarations at the same level (in either direction), or out of functions. You can otherwise jump forward and backward within a block (including past nested blocks) or out of a block.
- Possibility for a function called by one JavaScript program to suspend that program while executing a different JavaScript program (which may possibly share objects with the first one), and later resume execution.