# Codepages for JS

[Codepages](https://en.wikipedia.org/wiki/Codepage) are character encodings.  In
many contexts, single-byte character sets are used in lieu of standard multibyte
Unicode encodings.  They use 256 characters with a simple mapping.

[unicode.org](http://www.unicode.org/Public/MAPPINGS/) hosts lists of mappings.
The build script automatically downloads and parses the mappings in order to
generate the full script.  The `pages.csv` description in `codepage.md` controls
which codepages are used.

## Setup

In node:

    var cptable = require('codepage');

In the browser:

    <script src="cptable.js"></script>
    <script src="cputils.js"></script>

Alternatively, use the full version in the dist folder:

    <script src="cptable.full.js"></script>

The complete set of codepages is large due to some Double Byte Character Set
encodings.  A much smaller file that just includes SBCS codepages is provided in
this repo (`sbcs.js`), as well as a file for other projects (`cpexcel.js`)

If you know which codepages you need, you can include individual scripts for
each codepage.  The individual files are provided in the `bits/` directory.
For example, to include only the Mac codepages:

    <script src="bits/10000.js"></script>
    <script src="bits/10006.js"></script>
    <script src="bits/10007.js"></script>
    <script src="bits/10029.js"></script>
    <script src="bits/10079.js"></script>
    <script src="bits/10081.js"></script>

All of the browser scripts define and append to the `cptable` object.  To rename
the object, edit the `JSVAR` shell variable in `make.sh` and run the script.

The utilities functions are contained in `cputils.js`, which assumes that the
appropriate codepage scripts were loaded.

## Usage

The codepages are indexed by number.  To get the unicode character for a given
codepoint, use the `dec` property:

    var unicode_cp10000_255 = cptable[10000].dec[255]; // ˇ

To get the codepoint for a given character, use the `enc` property:

    var cp10000_711 = cptable[10000].enc[String.fromCharCode(711)]; // 255

There are a few utilities that deal with strings and buffers:

    var 汇总 = cptable.utils.decode(936, [0xbb,0xe3,0xd7,0xdc]);
    var buf =  cptable.utils.encode(936,  汇总);

`cptable.utils.encode(CP, data, ofmt)` accepts a String or Array of characters
and returns a representation controlled by `ofmt`:

- Default output is a Buffer (or Array) of bytes (integers between 0 and 255).
- If `ofmt == 'str'`, return a String where `o.charCodeAt(i)` is the ith byte
- If `ofmt == 'arr'`, return an Array of bytes

## Known Excel Codepages

A much smaller script, including only the codepages known to be used in Excel,
is available under the name `cpexcel`.  It exposes the same variable `cptable`
and is suitable as a drop-in replacement when the full codepage tables are not
needed.

In node:

    var cptable = require('codepage/dist/cpexcel.full');

## Building the script

This script uses [voc](npm.im/voc).  The script to build the codepage tables and
the JS source is `codepage.md`, so building is as simple as `voc codepage.md`.

## Generated Codepages

The complete list of hardcoded codepages can be found in the file `pages.csv`.

Some codepages are easier to implement algorithmically.  Since these are
hardcoded in utils, there is no corresponding entry (they are "magic")

| CP# |  Information  | Description |
| --: |  -----------  | ----------- |
|   37|  unicode.org  |IBM EBCDIC US-Canada
|  437|  unicode.org  |OEM United States
|  500|  unicode.org  |IBM EBCDIC International
|  708|MakeEncoding.cs|Arabic (ASMO 708)
|  720|MakeEncoding.cs|Arabic (Transparent ASMO); Arabic (DOS)
|  737|  unicode.org  |OEM Greek (formerly 437G); Greek (DOS)
|  775|  unicode.org  |OEM Baltic; Baltic (DOS)
|  850|  unicode.org  |OEM Multilingual Latin 1; Western European (DOS)
|  852|  unicode.org  |OEM Latin 2; Central European (DOS)
|  855|  unicode.org  |OEM Cyrillic (primarily Russian)
|  857|  unicode.org  |OEM Turkish; Turkish (DOS)
|  858|MakeEncoding.cs|OEM Multilingual Latin 1 + Euro symbol
|  860|  unicode.org  |OEM Portuguese; Portuguese (DOS)
|  861|  unicode.org  |OEM Icelandic; Icelandic (DOS)
|  862|  unicode.org  |OEM Hebrew; Hebrew (DOS)
|  863|  unicode.org  |OEM French Canadian; French Canadian (DOS)
|  864|  unicode.org  |OEM Arabic; Arabic (864)
|  865|  unicode.org  |OEM Nordic; Nordic (DOS)
|  866|  unicode.org  |OEM Russian; Cyrillic (DOS)
|  869|  unicode.org  |OEM Modern Greek; Greek, Modern (DOS)
|  870|MakeEncoding.cs|IBM EBCDIC Multilingual/ROECE (Latin 2)
|  874|  unicode.org  |Windows Thai
|  875|  unicode.org  |IBM EBCDIC Greek Modern
|  932|  unicode.org  |Japanese Shift-JIS
|  936|  unicode.org  |Simplified Chinese GBK
|  949|  unicode.org  |Korean
|  950|  unicode.org  |Traditional Chinese Big5
| 1026|  unicode.org  |IBM EBCDIC Turkish (Latin 5)
| 1047|MakeEncoding.cs|IBM EBCDIC Latin 1/Open System
| 1140|MakeEncoding.cs|IBM EBCDIC US-Canada (037 + Euro symbol)
| 1141|MakeEncoding.cs|IBM EBCDIC Germany (20273 + Euro symbol)
| 1142|MakeEncoding.cs|IBM EBCDIC Denmark-Norway (20277 + Euro symbol)
| 1143|MakeEncoding.cs|IBM EBCDIC Finland-Sweden (20278 + Euro symbol)
| 1144|MakeEncoding.cs|IBM EBCDIC Italy (20280 + Euro symbol)
| 1145|MakeEncoding.cs|IBM EBCDIC Latin America-Spain (20284 + Euro symbol)
| 1146|MakeEncoding.cs|IBM EBCDIC United Kingdom (20285 + Euro symbol)
| 1147|MakeEncoding.cs|IBM EBCDIC France (20297 + Euro symbol)
| 1148|MakeEncoding.cs|IBM EBCDIC International (500 + Euro symbol)
| 1149|MakeEncoding.cs|IBM EBCDIC Icelandic (20871 + Euro symbol)
| 1200|     magic     |Unicode UTF-16, little endian (BMP of ISO 10646)
| 1201|     magic     |Unicode UTF-16, big endian
| 1250|  unicode.org  |Windows Central Europe
| 1251|  unicode.org  |Windows Cyrillic
| 1252|  unicode.org  |Windows Latin I
| 1253|  unicode.org  |Windows Green
| 1254|  unicode.org  |Windows Turkish
| 1255|  unicode.org  |Windows Hebrew
| 1256|  unicode.org  |Windows Arabic
| 1257|  unicode.org  |Windows Baltic
| 1258|  unicode.org  |Windows Vietnam
| 1361|MakeEncoding.cs|Korean (Johab)
|10000|  unicode.org  |MAC Roman
|10001|MakeEncoding.cs|Japanese (Mac)
|10002|MakeEncoding.cs|MAC Traditional Chinese (Big5)
|10003|MakeEncoding.cs|Korean (Mac)
|10004|MakeEncoding.cs|Arabic (Mac)
|10005|MakeEncoding.cs|Hebrew (Mac)
|10006|  unicode.org  |Greek (Mac)
|10007|  unicode.org  |Cyrillic (Mac)
|10008|MakeEncoding.cs|MAC Simplified Chinese (GB 2312)
|10010|MakeEncoding.cs|Romanian (Mac)
|10017|MakeEncoding.cs|Ukrainian (Mac)
|10021|MakeEncoding.cs|Thai (Mac)
|10029|  unicode.org  |MAC Latin 2 (Central European)
|10079|  unicode.org  |Icelandic (Mac)
|10081|  unicode.org  |Turkish (Mac)
|10082|MakeEncoding.cs|Croatian (Mac)
|12000|     magic     |Unicode UTF-32, little endian byte order
|12001|     magic     |Unicode UTF-32, big endian byte order
|20000|MakeEncoding.cs|CNS Taiwan (Chinese Traditional)
|20001|MakeEncoding.cs|TCA Taiwan
|20002|MakeEncoding.cs|Eten Taiwan (Chinese Traditional)
|20003|MakeEncoding.cs|IBM5550 Taiwan
|20004|MakeEncoding.cs|TeleText Taiwan
|20005|MakeEncoding.cs|Wang Taiwan
|20105|MakeEncoding.cs|Western European IA5 (IRV International Alphabet 5) 7-bit
|20106|MakeEncoding.cs|IA5 German (7-bit)
|20107|MakeEncoding.cs|IA5 Swedish (7-bit)
|20108|MakeEncoding.cs|IA5 Norwegian (7-bit)
|20127|     magic     |US-ASCII (7-bit)
|20261|MakeEncoding.cs|T.61
|20269|MakeEncoding.cs|ISO 6937 Non-Spacing Accent
|20273|MakeEncoding.cs|IBM EBCDIC Germany
|20277|MakeEncoding.cs|IBM EBCDIC Denmark-Norway
|20278|MakeEncoding.cs|IBM EBCDIC Finland-Sweden
|20280|MakeEncoding.cs|IBM EBCDIC Italy
|20284|MakeEncoding.cs|IBM EBCDIC Latin America-Spain
|20285|MakeEncoding.cs|IBM EBCDIC United Kingdom
|20290|MakeEncoding.cs|IBM EBCDIC Japanese Katakana Extended
|20297|MakeEncoding.cs|IBM EBCDIC France
|20420|MakeEncoding.cs|IBM EBCDIC Arabic
|20423|MakeEncoding.cs|IBM EBCDIC Greek
|20424|MakeEncoding.cs|IBM EBCDIC Hebrew
|20833|MakeEncoding.cs|IBM EBCDIC Korean Extended
|20838|MakeEncoding.cs|IBM EBCDIC Thai
|20866|MakeEncoding.cs|Russian Cyrillic (KOI8-R)
|20871|MakeEncoding.cs|IBM EBCDIC Icelandic
|20880|MakeEncoding.cs|IBM EBCDIC Cyrillic Russian
|20905|MakeEncoding.cs|IBM EBCDIC Turkish
|20924|MakeEncoding.cs|IBM EBCDIC Latin 1/Open System (1047 + Euro symbol)
|20932|MakeEncoding.cs|Japanese (JIS 0208-1990 and 0212-1990)
|20936|MakeEncoding.cs|Simplified Chinese (GB2312-80)
|20949|MakeEncoding.cs|Korean Wansung
|21025|MakeEncoding.cs|IBM EBCDIC Cyrillic Serbian-Bulgarian
|21866|MakeEncoding.cs|Ukrainian Cyrillic (KOI8-U)
|28591|  unicode.org  |ISO 8859-1 Latin 1 (Western European)
|28592|  unicode.org  |ISO 8859-2 Latin 2 (Central European)
|28593|  unicode.org  |ISO 8859-3 Latin 3
|28594|  unicode.org  |ISO 8859-4 Baltic
|28595|  unicode.org  |ISO 8859-5 Cyrillic
|28596|  unicode.org  |ISO 8859-6 Arabic
|28597|  unicode.org  |ISO 8859-7 Greek
|28598|  unicode.org  |ISO 8859-8 Hebrew (ISO-Visual)
|28599|  unicode.org  |ISO 8859-9 Turkish
|28600|  unicode.org  |ISO 8859-10 Latin 6
|28601|  unicode.org  |ISO 8859-11 Latin (Thai)
|28603|  unicode.org  |ISO 8859-13 Latin 7 (Estonian)
|28604|  unicode.org  |ISO 8859-14 Latin 8 (Celtic)
|28605|  unicode.org  |ISO 8859-15 Latin 9
|28606|  unicode.org  |ISO 8859-15 Latin 10
|29001|MakeEncoding.cs|Europa 3
|38598|MakeEncoding.cs|ISO 8859-8 Hebrew (ISO-Logical)
|50220|MakeEncoding.cs|ISO 2022 JIS Japanese with no halfwidth Katakana
|50221|MakeEncoding.cs|ISO 2022 JIS Japanese with halfwidth Katakana
|50222|MakeEncoding.cs|ISO 2022 Japanese JIS X 0201-1989 (1 byte Kana-SO/SI)
|50225|MakeEncoding.cs|ISO 2022 Korean
|50227|MakeEncoding.cs|ISO 2022 Simplified Chinese
|51932|MakeEncoding.cs|EUC Japanese
|51936|MakeEncoding.cs|EUC Simplified Chinese
|51949|MakeEncoding.cs|EUC Korean
|52936|MakeEncoding.cs|HZ-GB2312 Simplified Chinese
|54936|MakeEncoding.cs|GB18030 Simplified Chinese (4 byte)
|57002|MakeEncoding.cs|ISCII Devanagari
|57003|MakeEncoding.cs|ISCII Bengali
|57004|MakeEncoding.cs|ISCII Tamil
|57005|MakeEncoding.cs|ISCII Telugu
|57006|MakeEncoding.cs|ISCII Assamese
|57007|MakeEncoding.cs|ISCII Oriya
|57008|MakeEncoding.cs|ISCII Kannada
|57009|MakeEncoding.cs|ISCII Malayalam
|57010|MakeEncoding.cs|ISCII Gujarati
|57011|MakeEncoding.cs|ISCII Punjabi
|65000|     magic     |Unicode (UTF-7)
|65001|     magic     |Unicode (UTF-8)

Note that MakeEncoding.cs deviates from unicode.org for some codepages.  In the
case of direct conflicts, unicode.org takes precedence.  In cases where the
unicode.org listing does not prescribe a value, MakeEncoding.cs value is used.

## Missing Codepages

The following codepages are not implemented. Normative references may not be
available in all cases.  Furthermore, other software packages are known to hack
certain codepages (for example, Mozilla treats ASMO-708 as an alias of Arabic
ISO-8869-6 when in fact there are many differences), so all implementations
*should* be cleanroom when possible.

- 709   Arabic (ASMO-449+, BCON V4)
- 710   Arabic - Transparent Arabic
- 21027 (deprecated) <-- is this necessary?
- 50229 ISO 2022 Traditional Chinese
- 50930 EBCDIC Japanese (Katakana) Extended
- 50931 EBCDIC US-Canada and Japanese
- 50933 EBCDIC Korean Extended and Korean
- 50935 EBCDIC Simplified Chinese Extended and Simplified Chinese
- 50936 EBCDIC Simplified Chinese
- 50937 EBCDIC US-Canada and Traditional Chinese
- 50939 EBCDIC Japanese (Latin) Extended and Japanese
- 51950 EUC Traditional Chinese

## Sources

- [Unicode Consortium Public Mappings](http://www.unicode.org/Public/MAPPINGS/)
- [Code Page Enumeration](http://msdn.microsoft.com/en-us/library/cc195051.aspx)
- [Code Page Identifiers](http://msdn.microsoft.com/en-us/library/windows/desktop/dd317756.aspx)

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