ICU StringPrep profiles

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0.8.08 years ago13 years agoMinified + gzip package size for node-stringprep in KB


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Exposes predefined Unicode normalization functions that are required by many protocols. This is just a binding to ICU, which is said to be fast..
If ICU is not available then we make use of JavaScript fallbacks.


var StringPrep = require('node-stringprep').StringPrep;
var prep = new StringPrep('nameprep');
prep.prepare('Äffchen')  // => 'äffchen'

For a list of supported profiles, see
Javascript fallbacks can be disabled/enabled using the following methods on the StringPrep object:
var prep = new StringPrep('resourceprep')

Javascript fallbacks are enabled by default. You can also check to see if native icu bindings can/will be used by calling the isNative() method:
var prep = new StringPrep('resourceprep')
prep.isNative()  // true or false

We also implement the ToASCII and ToUnicode operations as defined in the IDNA RFC 3490. These routines convert Unicode to ASCII with NamePrep and then with Punycode, and vice versa.
var nodeStringPrep = require('node-stringprep');
nodeStringPrep.toASCII('i♥u') // 'xn--iu-t0x'
nodeStringPrep.toUnicode('xn--iu-t0x') // 'i♥u'

The operations can be finessed with an optional second argument, a set of boolean flags:
nodeStringPrep.toASCII('i♥u', {
    allowUnassigned: true, // allow unassigned code points to be converted
    throwIfError: true, // throw exception if error, don't return string unchanged
    useSTD3Rules: true // use the STD3 ASCII rules for host names
nodeStringPrep.toUnicode('xn--iu-t0x', {
    allowUnassigned: true // allow unassigned code points to be converted


npm i node-stringprep

If libicu isn't available installation will gracefully fail and javascript fallbacks will be used.
If experiencing issues with node-gyp please see which may be able to help.


apt-get install libicu-dev

RedHat & Centos

yum install libicu-devel

Gentoo ###

emerge icu



port install icu +devel


sudo ln -s /opt/boxen/homebrew/Cellar/icu4c/52.1/bin/icu-config /usr/local/bin/icu-config
sudo ln -s /opt/boxen/homebrew/Cellar/icu4c/52.1/include/* /usr/local/include


brew install icu4c
ln -s /usr/local/Cellar/icu4c/<VERSION>/bin/icu-config /usr/local/bin/icu-config
ln -s /usr/local/Cellar/icu4c/<VERSION>/include/* /usr/local/include
If experiencing issues with 'homebrew' installing version 50.1 of icu4c, try the following:
brew search icu4c
brew tap homebrew/versions
brew versions icu4c
cd $(brew --prefix) && git pull --rebase
git checkout c25fd2f $(brew --prefix)/Library/Formula/icu4c.rb
brew install icu4c

Running Tests

npm test