• Our JavaScript syntax tree should support two kind of strings: sequences of bytes (which is what is currently available) and UTF8 strings.
• When outputting UTF8 strings, one does not need to escape bytes above 127.
• The JavaScript parser should unescape the UTF8 parsed strings.
• The JavaScript parser should unescape regular expressions.
• When generating a regular expression literal, one should check whether it contains only allowed characters.

(See the ECMAScript spec for details on the syntax of literal strings and regular expressions.)