codepage

What is codepage?

The codepage npm package is a library for converting data between different character encodings. It supports a wide range of code pages and provides functionality for encoding and decoding text.

What are codepage's main functionalities?

Encoding Conversion

Convert strings between different encodings. In this example, we convert a binary string to UTF-8 and vice versa using code page 437.

var cp = require('codepage');
var utf8String = cp.utils.decode(437, Buffer.from('Hello World', 'binary'));
var binaryString = cp.utils.encode(437, 'Hello World');

Stream Transformation

Create a stream that transforms data from one encoding to another. Here, we create a transform stream that encodes incoming data to code page 437.

var cp = require('codepage');
var stream = require('stream');
var converter = new stream.Transform();
converter._transform = function(chunk, encoding, done) {
  this.push(cp.utils.encode(437, chunk.toString()));
done();
};

Handling Code Pages

Access information about different code pages. This code sample retrieves information about code page 437.

var cp = require('codepage');
var cpInfo = cp[437];
console.log(cpInfo.name);

Other packages similar to codepage

iconv-lite

iconv-lite is a popular character encoding conversion library that works similarly to codepage. It supports many encodings and is often used for its simplicity and lightweight nature. Unlike codepage, iconv-lite does not rely on native Node.js modules, making it more portable across different platforms.

buffer-encoding

buffer-encoding is another package that offers encoding and decoding of text in Node.js. It provides a simple API for converting between different character encodings. It is similar to codepage but has a smaller footprint and fewer dependencies.

text-encoding

text-encoding is a polyfill for the Encoding Living Standard API provided by the WHATWG. It allows for encoding and decoding of text in the browser and Node.js. It is more comprehensive than codepage as it aims to provide a polyfill for the standard API, but it might be heavier in terms of size and complexity.

README

js-codepage

Codepages are character encodings. In many contexts, single- or double-byte character sets are used in lieu of Unicode encodings. The codepages map between characters and numbers.

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.

The script will manipulate module.exports if available (e.g. in a CommonJS require context). This is not always desirable. To prevent the behavior, define DO_NOT_EXPORT_CODEPAGE.

Usage

Most 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);
var sushi= cptable.utils.decode(65001, [0xf0,0x9f,0x8d,0xa3]); // 🍣
var sbuf = cptable.utils.encode(65001, sushi);

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 i-th byte
• If ofmt == 'arr', return an Array of bytes

cptable.utils.decode(CP, data) accepts a byte String or Array of numbers or Buffer and returns a JS string.

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');

Rolling your own script

The make.sh script in the repo can take a manifest and generate JS source.

Usage:

$ bash make.sh path_to_manifest output_file_name JSVAR

where

• JSVAR is the name of the exported variable (generally cptable)
• output_file_name is the output file (e.g. cpexcel.js, cptable.js)
• path_to_manifest is the path to the manifest file.

The manifest file is expected to be a CSV with 3 columns:

<codepage number>,<source>,<size>

If a source is specified, it will try to download the specified file and parse. The file format is expected to follow the format from the unicode.org site. The size should be 1 for a single-byte codepage and 2 for a double-byte codepage. For mixed codepages (which use some single- and some double-byte codes), the script assumes the mapping is a prefix code and generates efficient JS code.

Generated scripts only include the mapping. cat a mapping with cputils.js to produce a complete script like cpexcel.full.js.

Building the complete script

This script uses 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#	Source	Description
37	unicode.org	IBM EBCDIC US-Canada
437	unicode.org	OEM United States
500	unicode.org	IBM EBCDIC International
620	NLS	Mazovia (Polish) MS-DOS
708	Windows 7	Arabic (ASMO 708)
720	Windows 7	Arabic (Transparent ASMO); Arabic (DOS)
737	unicode.org	OEM Greek (formerly 437G); Greek (DOS)
775	unicode.org	OEM Baltic; Baltic (DOS)
808	unicode.org	OEM Russian; Cyrillic + Euro symbol
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	Windows 7	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	Windows 7	IBM EBCDIC Multilingual/ROECE (Latin 2)
872	unicode.org	OEM Cyrillic (primarily Russian) + Euro Symbol
874	unicode.org	Windows Thai
875	unicode.org	IBM EBCDIC Greek Modern
895	NLS	Kamenický (Czech) MS-DOS
932	unicode.org	Japanese Shift-JIS
936	unicode.org	Simplified Chinese GBK
949	unicode.org	Korean
950	unicode.org	Traditional Chinese Big5
1010	IBM	IBM EBCDIC French
1026	unicode.org	IBM EBCDIC Turkish (Latin 5)
1047	Windows 7	IBM EBCDIC Latin 1/Open System
1132	IBM	IBM EBCDIC Lao (1132 / 1133 / 1341)
1140	Windows 7	IBM EBCDIC US-Canada (037 + Euro symbol)
1141	Windows 7	IBM EBCDIC Germany (20273 + Euro symbol)
1142	Windows 7	IBM EBCDIC Denmark-Norway (20277 + Euro symbol)
1143	Windows 7	IBM EBCDIC Finland-Sweden (20278 + Euro symbol)
1144	Windows 7	IBM EBCDIC Italy (20280 + Euro symbol)
1145	Windows 7	IBM EBCDIC Latin America-Spain (20284 + Euro symbol)
1146	Windows 7	IBM EBCDIC United Kingdom (20285 + Euro symbol)
1147	Windows 7	IBM EBCDIC France (20297 + Euro symbol)
1148	Windows 7	IBM EBCDIC International (500 + Euro symbol)
1149	Windows 7	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 Greek
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	Windows 7	Korean (Johab)
10000	unicode.org	MAC Roman
10001	Windows 7	Japanese (Mac)
10002	Windows 7	MAC Traditional Chinese (Big5)
10003	Windows 7	Korean (Mac)
10004	Windows 7	Arabic (Mac)
10005	Windows 7	Hebrew (Mac)
10006	unicode.org	Greek (Mac)
10007	unicode.org	Cyrillic (Mac)
10008	Windows 7	MAC Simplified Chinese (GB 2312)
10010	Windows 7	Romanian (Mac)
10017	Windows 7	Ukrainian (Mac)
10021	Windows 7	Thai (Mac)
10029	unicode.org	MAC Latin 2 (Central European)
10079	unicode.org	Icelandic (Mac)
10081	unicode.org	Turkish (Mac)
10082	Windows 7	Croatian (Mac)
12000	magic	Unicode UTF-32, little endian byte order
12001	magic	Unicode UTF-32, big endian byte order
20000	Windows 7	CNS Taiwan (Chinese Traditional)
20001	Windows 7	TCA Taiwan
20002	Windows 7	Eten Taiwan (Chinese Traditional)
20003	Windows 7	IBM5550 Taiwan
20004	Windows 7	TeleText Taiwan
20005	Windows 7	Wang Taiwan
20105	Windows 7	Western European IA5 (IRV International Alphabet 5)
20106	Windows 7	IA5 German (7-bit)
20107	Windows 7	IA5 Swedish (7-bit)
20108	Windows 7	IA5 Norwegian (7-bit)
20127	magic	US-ASCII (7-bit)
20261	Windows 7	T.61
20269	Windows 7	ISO 6937 Non-Spacing Accent
20273	Windows 7	IBM EBCDIC Germany
20277	Windows 7	IBM EBCDIC Denmark-Norway
20278	Windows 7	IBM EBCDIC Finland-Sweden
20280	Windows 7	IBM EBCDIC Italy
20284	Windows 7	IBM EBCDIC Latin America-Spain
20285	Windows 7	IBM EBCDIC United Kingdom
20290	Windows 7	IBM EBCDIC Japanese Katakana Extended
20297	Windows 7	IBM EBCDIC France
20420	Windows 7	IBM EBCDIC Arabic
20423	Windows 7	IBM EBCDIC Greek
20424	Windows 7	IBM EBCDIC Hebrew
20833	Windows 7	IBM EBCDIC Korean Extended
20838	Windows 7	IBM EBCDIC Thai
20866	Windows 7	Russian Cyrillic (KOI8-R)
20871	Windows 7	IBM EBCDIC Icelandic
20880	Windows 7	IBM EBCDIC Cyrillic Russian
20905	Windows 7	IBM EBCDIC Turkish
20924	Windows 7	IBM EBCDIC Latin 1/Open System (1047 + Euro symbol)
20932	Windows 7	Japanese (JIS 0208-1990 and 0212-1990)
20936	Windows 7	Simplified Chinese (GB2312-80)
20949	Windows 7	Korean Wansung
21025	Windows 7	IBM EBCDIC Cyrillic Serbian-Bulgarian
21027	NLS	Extended/Ext Alpha Lowercase
21866	Windows 7	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	Windows 7	Europa 3
38598	Windows 7	ISO 8859-8 Hebrew (ISO-Logical)
47451	unicode.org	Atari ST/TT
50220	Windows 7	ISO 2022 JIS Japanese with no halfwidth Katakana
50221	Windows 7	ISO 2022 JIS Japanese with halfwidth Katakana
50222	Windows 7	ISO 2022 Japanese JIS X 0201-1989 (1 byte Kana-SO/SI)
50225	Windows 7	ISO 2022 Korean
50227	Windows 7	ISO 2022 Simplified Chinese
51932	Windows 7	EUC Japanese
51936	Windows 7	EUC Simplified Chinese
51949	Windows 7	EUC Korean
52936	Windows 7	HZ-GB2312 Simplified Chinese
54936	Windows 7	GB18030 Simplified Chinese (4 byte)
57002	Windows 7	ISCII Devanagari
57003	Windows 7	ISCII Bengali
57004	Windows 7	ISCII Tamil
57005	Windows 7	ISCII Telugu
57006	Windows 7	ISCII Assamese
57007	Windows 7	ISCII Oriya
57008	Windows 7	ISCII Kannada
57009	Windows 7	ISCII Malayalam
57010	Windows 7	ISCII Gujarati
57011	Windows 7	ISCII Punjabi
65000	magic	Unicode (UTF-7)
65001	magic	Unicode (UTF-8)

unicode.org refers to the Unicode Consortium Public Mappings, a database of various mappings between unicode characters and respective character sets. The tables are processed by a few scripts in the build process.

IBM refers to the IBM coded character set database. Even though IBM uses a different numbering scheme from Windows, the IBM numbers are used when there is no conflict. The tables are manually generated from the symbol PDFs.

Windows 7 refers to direct inspection of Windows 7 machines using .NET class System.Text.Encoding. The enclosed MakeEncoding.cs C# program brute-forces code pages. MakeEncoding.cs deviates from unicode.org in some cases. When they map a given code to different characters, unicode.org value is used. When unicode.org does not prescribe a value, MakeEncoding.cs value is used.

NLS refers to the National Language Support files supplied in various versions of Windows. In older versions of Windows (e.g. Windows 98) these files followed the name pattern CP_#.NLS, but newer versions use the name pattern C_#.NLS.

Testing

make test will run the nodejs-based test.

To run the in-browser tests, run a local server and go to the ctest directory. make ctestserv will start a python SimpleHTTPServer server on port 8000.

To update the browser artifacts, run make ctest.

Sources

• Unicode Consortium Public Mappings
• Windows Code Page Enumeration
• Windows Code Page Identifiers
• IBM Coded Character Sets

License

Please consult the attached LICENSE file for details. All rights not explicitly granted by the Apache 2.0 license are reserved by the Original Author.

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