iconv-lite

What is iconv-lite?

The iconv-lite npm package provides utilities for converting character encodings in pure JavaScript. It supports many different encodings and can convert to and from Buffer objects without the need for a native C++ binding. This makes it a lightweight and portable solution for encoding conversion.

What are iconv-lite's main functionalities?

Encoding Conversion

Converts text from one character encoding to another. The example shows how to decode a buffer to a string and encode a string to a buffer using Windows-1251 encoding.

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

// Convert from an encoded buffer to js string.
const str = iconv.decode(Buffer.from([0x63, 0x61, 0x66, 0xe9]), 'win1251');

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

Streaming Conversion

Provides a streaming interface for encoding conversion. This example demonstrates how to create a read stream from a file and pipe it through iconv-lite's decode stream.

const iconv = require('iconv-lite');
const fs = require('fs');

// Decode stream (from a file, for example)
const readStream = fs.createReadStream('file.txt');
const decodeStream = iconv.decodeStream('win1251');

readStream.pipe(decodeStream);

decodeStream.on('data', function(str) {
  console.log(str); // converted text
});

Encoding Detection

Checks if a particular encoding is supported by iconv-lite. The example checks if UTF-8 encoding is supported.

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

// Check if encoding is supported
const encodingSupported = iconv.encodingExists('utf-8');

console.log(encodingSupported); // true or false

Other packages similar to iconv-lite

buffer

The 'buffer' package is a Node.js core module that provides a way to handle binary data. It does not offer direct encoding conversion like iconv-lite, but it can be used in conjunction with other modules to achieve similar results.

iconv

The 'iconv' package is similar to iconv-lite but relies on native C++ bindings. It provides more comprehensive encoding support but is not as lightweight or portable as iconv-lite due to its compiled components.

string_decoder

The 'string_decoder' module is a Node.js core module that provides an API for decoding Buffer objects into strings using a specified character encoding. It is less feature-rich compared to iconv-lite and does not support as many encodings.

README

Pure JS character encoding conversion

• Doesn't need native code compilation. Works on Windows and in sandboxed environments like Cloud9.
• 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
• Streaming support for Node v0.10+
• Can extend Node.js primitives (buffers, streams) to support all iconv-lite encodings.
• In-browser usage via Browserify (~180k gzip compressed with Buffer shim included).
• License: MIT.

Usage

Basic API

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

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

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

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

Streaming API (Node v0.10+)

// Decode stream (from binary 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
    });
});

Extend Node.js own encodings

// After this call all Node basic primitives will understand iconv-lite encodings.
iconv.extendNodeEncodings();

// Examples:
buf = new Buffer(str, 'win1251');
buf.write(str, 'gbk');
str = buf.toString('latin1');
assert(Buffer.isEncoding('iso-8859-15'));
Buffer.byteLength(str, 'us-ascii');

http.createServer(function(req, res) {
    req.setEncoding('big5');
    req.collect(function(err, body) {
        console.log(body);
    });
});

fs.createReadStream("file.txt", "shift_jis");

// External modules are also supported (if they use Node primitives, which they probably do).
request = require('request');
request({
    url: "http://github.com/", 
    encoding: "cp932"
});

// To remove extensions
iconv.undoExtendNodeEncodings();

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.
• 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, GB2313, 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.
• 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.

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 [e-mail]: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

Adoption