Subj : Re: About Unicode
To   : netscape.public.mozilla.jseng
From : Jens Thiele
Date : Mon Nov 22 2004 09:18 pm

Jun Kim schrieb:
> Hi. I have a question about unicode.
> Well, I don't know whether I can ask this question here,
> but I'll ask anyway. Any guideline will be appreciated.
> I'm using the unicode language, preferably Korean.
> And I thought JS engine support unicode string, but apparently not.

ECMAScript (=3D>JavaScript) strings support unicode.
And the JS engine (I assume you mean the one written in C -
"SpiderMonkey") supports them, too.

ECMAScript Language Specification Edition 3 (24-Mar-00):

"8.4 The String Type
The String type is the set of all finite ordered sequences of zero or
more 16-bit unsigned integer values [...] When a string contains actual
textual data, each element is considered to be a single UTF-16 unit.
[...] NOTE: The rationale behind these decisions was to keep the
implementation of Strings as simple and high-performing as possible. The
intent is that textual data coming into the execution environment from
outside (e.g., user input, text read from a file or received over the
network, etc.) be converted to Unicode Normalised Form C before the
running program sees it. Usually this would occur at the same time
incoming text is converted from its original character encoding to
Unicode (and would impose no additional overhead). Since it is
recommended that ECMAScript source code be in Normalised Form C, string
literals are guaranteed to be normalised (if source text is guaranteed
to be normalised), as long as they do not contain any Unicode escape
sequences."

> (or maybe I'm doing it wrong)
>=20
> Well, this is the piece of the codes:
>=20
>   js> var a =3D "=EA=B0=80=EB=82=98=EB=8B=A4";      // the string is un=
icode
>   js> a.charAt(1);            // this returns a trash character

this probably is the example shell included in the spidermonkey
distribution? it does not support unicode or perhaps better:
it doesn't do what is mentioned in the NOTE above.
It simply reads bytes/chars and passes them to JS_CompileScript:
http://lxr.mozilla.org/mozilla/source/js/src/js.c#357

see also:
http://www.mozilla.org/js/spidermonkey/apidoc/gen/api-JS_CompileScript.ht=
ml
vs.
http://www.mozilla.org/js/spidermonkey/apidoc/gen/api-JS_CompileUCScript.=
html
(the byte string is treated as iso-latin)

Greetings
Jens

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