Full Unicode based on UTF-16 proposal

Erik Corry erik.corry at gmail.com
Fri Mar 16 01:55:46 PDT 2012

This is very useful, and was surely a lot of work.  I like the general
thrust of it a lot.  It has a high level of backwards compatibility,
does not rely on the VM having two different string implementations in
it, and it seems to fix the issues people are encountering.

However I think we probably do want the /u modifier on regexps to
control the new backward-incompatible behaviour.  There may be some
way to relax this for regexp literals in opted in Harmony code, but
for new RegExp(...) and for other string literals I think there are
rather too many inconsistencies with the old behaviour.

The algorithm given for codePointAt never returns NaN.  It should
probably do that for indices that hit a trail surrogate that has a
lead surrogate preceeding it.

Perhaps it is outside the scope of this proposal, but it would also
make a lot of sense to add some named character classes to RegExp.

If we are makig a /u modifier for RegExp it would also be nice to get
rid of the incorrect case independent matching rules.  This is the
section that says: "If ch's code unit value is greater than or equal
to decimal 128 and cu's code unit value is less than decimal  128,
then return ch."

2012/3/16 Norbert Lindenberg <ecmascript at norbertlindenberg.com>:
> Based on my prioritization of goals for support for full Unicode in ECMAScript [1], I've put together a proposal for supporting the full Unicode character set based on the existing representation of text in ECMAScript using UTF-16 code unit sequences:
> http://norbertlindenberg.com/2012/03/ecmascript-supplementary-characters/index.html
> The detailed proposed spec changes serve to get a good idea of the scope of the changes, but will need some polishing.
> Comments?
> Thanks,
> Norbert
> [1] https://mail.mozilla.org/pipermail/es-discuss/2012-February/020721.html
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