punycode

What is punycode?

The punycode npm package is a robust library for encoding and decoding Unicode with Punycode. It's useful for internationalization and handling Unicode domain names and email addresses.

What are punycode's main functionalities?

Encoding to Punycode

Converts a Unicode string to a Punycode string (ASCII). Mainly used for domain names.

punycode.encode('mañana') // => 'maana-pta'

Decoding from Punycode

Converts a Punycode string (ASCII) back to a Unicode string. Useful for displaying human-readable text.

punycode.decode('maana-pta') // => 'mañana'

Unicode to ASCII conversion for domain names

Converts a Unicode domain name to an ASCII-compatible encoding (ACE) domain name.

punycode.toASCII('español.example.com') // => 'xn--espaol-zwa.example.com'

ASCII to Unicode conversion for domain names

Converts an ASCII-compatible encoding (ACE) domain name back to a Unicode domain name.

punycode.toUnicode('xn--espaol-zwa.example.com') // => 'español.example.com'

Other packages similar to punycode

idna-uts46-hx

A library that implements IDNA (Internationalized Domain Names in Applications) to Punycode conversion using the latest Unicode version. It's similar to punycode but follows the IDNA 2008 protocol, which is more up-to-date compared to the IDNA 2003 protocol that punycode follows.

README

Punycode.js

Punycode.js is a robust Punycode converter that fully complies to RFC 3492 and RFC 5891.

This JavaScript library is the result of comparing, optimizing and documenting different open-source implementations of the Punycode algorithm:

• The C example code from RFC 3492
• punycode.c by Markus W. Scherer (IBM)
• punycode.c by Ben Noordhuis
• JavaScript implementation by some
• punycode.js by Ben Noordhuis (note: not fully compliant)

This project was bundled with Node.js from v0.6.2+ until v7 (soft-deprecated).

This project provides a CommonJS module that uses ES2015+ features and JavaScript module, which work in modern Node.js versions and browsers. For the old Punycode.js version that offers the same functionality in a UMD build with support for older pre-ES2015 runtimes, including Rhino, Ringo, and Narwhal, see v1.4.1.

Installation

Via npm:

npm install punycode --save

In Node.js:

⚠️ Note that userland modules don't hide core modules. For example, require('punycode') still imports the deprecated core module even if you executed npm install punycode. Use require('punycode/') to import userland modules rather than core modules.

const punycode = require('punycode/');

API

punycode.decode(string)

Converts a Punycode string of ASCII symbols to a string of Unicode symbols.

// decode domain name parts
punycode.decode('maana-pta'); // 'mañana'
punycode.decode('--dqo34k'); // '☃-⌘'

punycode.encode(string)

Converts a string of Unicode symbols to a Punycode string of ASCII symbols.

// encode domain name parts
punycode.encode('mañana'); // 'maana-pta'
punycode.encode('☃-⌘'); // '--dqo34k'

punycode.toUnicode(input)

Converts a Punycode string representing a domain name or an email address to Unicode. Only the Punycoded parts of the input will be converted, i.e. it doesn’t matter if you call it on a string that has already been converted to Unicode.

// decode domain names
punycode.toUnicode('xn--maana-pta.com');
// → 'mañana.com'
punycode.toUnicode('xn----dqo34k.com');
// → '☃-⌘.com'

// decode email addresses
punycode.toUnicode('джумла@xn--p-8sbkgc5ag7bhce.xn--ba-lmcq');
// → 'джумла@джpумлатест.bрфa'

punycode.toASCII(input)

Converts a lowercased Unicode string representing a domain name or an email address to Punycode. Only the non-ASCII parts of the input will be converted, i.e. it doesn’t matter if you call it with a domain that’s already in ASCII.

// encode domain names
punycode.toASCII('mañana.com');
// → 'xn--maana-pta.com'
punycode.toASCII('☃-⌘.com');
// → 'xn----dqo34k.com'

// encode email addresses
punycode.toASCII('джумла@джpумлатест.bрфa');
// → 'джумла@xn--p-8sbkgc5ag7bhce.xn--ba-lmcq'

punycode.ucs2

punycode.ucs2.decode(string)

Creates an array containing the numeric code point values of each Unicode symbol in the string. While JavaScript uses UCS-2 internally, this function will convert a pair of surrogate halves (each of which UCS-2 exposes as separate characters) into a single code point, matching UTF-16.

punycode.ucs2.decode('abc');
// → [0x61, 0x62, 0x63]
// surrogate pair for U+1D306 TETRAGRAM FOR CENTRE:
punycode.ucs2.decode('\uD834\uDF06');
// → [0x1D306]

punycode.ucs2.encode(codePoints)

Creates a string based on an array of numeric code point values.

punycode.ucs2.encode([0x61, 0x62, 0x63]);
// → 'abc'
punycode.ucs2.encode([0x1D306]);
// → '\uD834\uDF06'

punycode.version

A string representing the current Punycode.js version number.

For maintainers

How to publish a new release

1. On the main branch, bump the version number in package.json:

   npm version patch -m 'Release v%s'
   

   Instead of patch, use minor or major as needed.

   Note that this produces a Git commit + tag.

2. Push the release commit and tag:

   git push && git push --tags
   

   Our CI then automatically publishes the new release to npm, under both the punycode and punycode.js names.

Author

Mathias Bynens

License

Punycode.js is available under the MIT license.