Javascript convert windows 1251 to utf 8

let utf8decoder = new TextDecoder(); // default 'utf-8' or 'utf8'

let u8arr = new Uint8Array([240, 160, 174, 183]);
let i8arr = new Int8Array([-16, -96, -82, -73]);
let u16arr = new Uint16Array([41200, 47022]);
let i16arr = new Int16Array([-24336, -18514]);
let i32arr = new Int32Array([-1213292304]);

console.log(utf8decoder.decode(u8arr));
console.log(utf8decoder.decode(i8arr));
console.log(utf8decoder.decode(u16arr));
console.log(utf8decoder.decode(i16arr));
console.log(utf8decoder.decode(i32arr));

const win1251decoder = new TextDecoder("windows-1251");
const bytes = new Uint8Array([
  207, 240, 232, 226, 229, 242, 44, 32, 236, 232, 240, 33,
]);
console.log(win1251decoder.decode(bytes)); // Привет, мир!

Specifications

Browser compatibility

BCD tables only load in the browser

iconv-lite: Pure JS character encoding conversion

• No need for native code compilation. Quick to install, works on Windows, Web, and in sandboxed environments.
• Used in popular projects like Express.js (body_parser),
  Grunt, Nodemailer, Yeoman and others.
• Faster than node-iconv (see below for performance comparison).
• Intuitive encode/decode API, including Streaming support.
• In-browser usage via browserify or webpack (~180kb gzip compressed with Buffer shim included).
• Typescript type definition file included.
• React Native is supported (need to install stream module to enable Streaming API).
• License: MIT.

Usage

Basic API

var iconv = require('iconv-lite');

// Convert from an encoded buffer to a js string.
str = iconv.decode(Buffer.from([0x68, 0x65, 0x6c, 0x6c, 0x6f]), 'win1251');

// Convert from a js string to an encoded buffer.
buf = iconv.encode("Sample input string", 'win1251');

// Check if encoding is supported
iconv.encodingExists("us-ascii")

Streaming API

// Decode stream (from binary data stream to js strings)
http.createServer(function(req, res) {
    var converterStream = iconv.decodeStream('win1251');
    req.pipe(converterStream);

    converterStream.on('data', function(str) {
        console.log(str); // Do something with decoded strings, chunk-by-chunk.
    });
});

// Convert encoding streaming example
fs.createReadStream('file-in-win1251.txt')
    .pipe(iconv.decodeStream('win1251'))
    .pipe(iconv.encodeStream('ucs2'))
    .pipe(fs.createWriteStream('file-in-ucs2.txt'));

// Sugar: all encode/decode streams have .collect(cb) method to accumulate data.
http.createServer(function(req, res) {
    req.pipe(iconv.decodeStream('win1251')).collect(function(err, body) {
        assert(typeof body == 'string');
        console.log(body); // full request body string
    });
});

Supported encodings

• All node.js native encodings: utf8, ucs2 / utf16-le, ascii, binary, base64, hex.
• Additional unicode encodings: utf16, utf16-be, utf-7, utf-7-imap, utf32, utf32-le, and utf32-be.
• All widespread singlebyte encodings: Windows 125x family, ISO-8859 family,
  IBM/DOS codepages, Macintosh family, KOI8 family, all others supported by iconv library.
  Aliases like ‘latin1’, ‘us-ascii’ also supported.
• All widespread multibyte encodings: CP932, CP936, CP949, CP950, GB2312, GBK, GB18030, Big5, Shift_JIS, EUC-JP.

See all supported encodings on wiki.

Most singlebyte encodings are generated automatically from node-iconv. Thank you Ben Noordhuis and libiconv authors!

Multibyte encodings are generated from Unicode.org mappings and WHATWG Encoding Standard mappings. Thank you, respective authors!

Encoding/decoding speed

Comparison with node-iconv module (1000x256kb, on MacBook Pro, Core i5/2.6 GHz, Node v0.12.0).
Note: your results may vary, so please always check on your hardware.

operation             iconv@2.1.4   iconv-lite@0.4.7
----------------------------------------------------------
encode('win1251')     ~96 Mb/s      ~320 Mb/s
decode('win1251')     ~95 Mb/s      ~246 Mb/s

BOM handling

• Decoding: BOM is stripped by default, unless overridden by passing stripBOM: false in options
  (f.ex. iconv.decode(buf, enc, {stripBOM: false})).
  A callback might also be given as a stripBOM parameter — it’ll be called if BOM character was actually found.
• If you want to detect UTF-8 BOM when decoding other encodings, use node-autodetect-decoder-stream module.
• Encoding: No BOM added, unless overridden by addBOM: true option.

UTF-16 Encodings

This library supports UTF-16LE, UTF-16BE and UTF-16 encodings. First two are straightforward, but UTF-16 is trying to be
smart about endianness in the following ways:

• Decoding: uses BOM and ‘spaces heuristic’ to determine input endianness. Default is UTF-16LE, but can be
  overridden with defaultEncoding: 'utf-16be' option. Strips BOM unless stripBOM: false.
• Encoding: uses UTF-16LE and writes BOM by default. Use addBOM: false to override.

UTF-32 Encodings

This library supports UTF-32LE, UTF-32BE and UTF-32 encodings. Like the UTF-16 encoding above, UTF-32 defaults to UTF-32LE, but uses BOM and ‘spaces heuristics’ to determine input endianness.

• The default of UTF-32LE can be overridden with the defaultEncoding: 'utf-32be' option. Strips BOM unless stripBOM: false.
• Encoding: uses UTF-32LE and writes BOM by default. Use addBOM: false to override. (defaultEncoding: 'utf-32be' can also be used here to change encoding.)

Other notes

When decoding, be sure to supply a Buffer to decode() method, otherwise bad things usually happen.
Untranslatable characters are set to � or ?. No transliteration is currently supported.
Node versions 0.10.31 and 0.11.13 are buggy, don’t use them (see #65, #77).

Testing

$ git clone git@github.com:ashtuchkin/iconv-lite.git
$ cd iconv-lite
$ npm install
$ npm test
    
$ # To view performance:
$ node test/performance.js

$ # To view test coverage:
$ npm run coverage
$ open coverage/lcov-report/index.html