Pomo

Pomo is a powerful implementation of gettext/dpgettext for Javascript that can be run both in the browser and Node as-is. It both reads PO files into memory and utilizes them for internationalization purposes.

Pomo reads PO files, eventually also MO files, and can load them from AJAX, special tags and literal strings as explained below.

Pomo provides a simplistic interface to work with complex scenarios, being able to handle * term contexts (some terms in a given context might very well not mean the same thing in a different context) * term plurals * multiline msgid and msgstr definitions (except for plurals).

For more information, check the release notes

Usage example

//Browser example. Server would have it the same, just after calling Pomo = require('./pomo.js')
window.onload = function() {
    /*
    Set a default domain for the Pomo.getText calls. If omitted,
    all calls to getText need to pass the domain set on Pomo.load,
    unless none was passed, in which case getText doesn't require a domain
  */
    Pomo.domain = 'translation_domain';

    //return a plain string instead of a translation object
    Pomo.returnStrings = true;

    //Return unescaped strings ready for insertion instead of the original literal escaped string
    Pomo.unescapeStrings = true;

    //Let's load from a literal
    Pomo.load('\
        #: /path/to/file.php:110 \
        msgctxt "some context" \
        msgid "String to translate, with %s markers" \
        msgstr "Cadena a traducir, con marcadores de %s" \
    ', //the literal PO contents
    {
        format: 'po', // the file format, can potentially be 'po' or 'mo'
        mode: 'literal', // wether the passed resource is a 'literal', a 'link' or a 'remote' file
        translation_domain: 'translation_domain' //Loaded resources will be put under this domain if set.
    });

    var p = document.createElement('p');
    p.appendChild(
    document.createTextNode(
    Pomo.getText("String to translate, with %s markers", {
        variables: ["tipo printf"], //only needed if you pass markers
        context: 'optional context',
        /* if there is a context, a search is made
                             for the translation mapping to it               */
        domain: 'translation_domain'
        /* Only mandatory if there's an actual domain in use
                                and no default one was set via Pomo.domain */
    })));
    document.documentElement.appendChild(p);

    //now let's load from any amounts of <link type="text/x-gettext-translation"/> you might have on the page
    var lnk_deferred = Pomo.load(null, {
        format: 'po',
        mode: 'link', //the new mode, tells Pomo to find a <link id="%LINK_ELEMENT_NAME%" and fetch it
        translation_domain: 'entirely_different_translation_domain' //this one we'll put in another translation_domain
    });
        
    /*
    Pomo.load now returns a Deferred object, which can execute the
    passed function upon parsing all the remote data. The passed function will have this = the Pomo instance
  */
    lnk_deferred.ready(function() {
        var p = document.createElement('p');
        p.appendChild(
        document.createTextNode(
        this.getText("String to translate, with %s markers", {
            variables: ["printf-ish"],
            context: 'optional context',
            domain: 'entirely_different_translation_domain'
        })));

        document.documentElement.appendChild(p);
    });

    /*
    And now another translation_domain from a straight AJAX call
  */
    var ajax_deferred = Pomo.load('/ajax/valid/url', {
        format: 'po',
        mode: 'ajax',
        translation_domain: 'a_third_translation_domain'
    });

    /*
    The deferred object works exactly the same way, only this time we're making use of the last loaded domain.
  */
    ajax_deferred.ready(function() {
        var p = document.createElement('p');
        p.appendChild(
        document.createTextNode(
        this.getText("String to translate, with %s markers", {
            variables: ["printf-ish"],
            context: 'optional context',
            domain: 'a_third_translation_domain'
        })));

        document.documentElement.appendChild(p);
    });
};

A pretty thing to do is aliasing Pomo.getText(); to __(), like this:.

var __ = (function(){
  var _ = !!window.Pomo? window.Pomo : (!!window.__Pomo? window.__Pomo: false); //is Pomo there? get it
  var gettext_wrap = function(word, options){return _.getText(word, options)};  // aliases getText
  gettext_wrap = !!_? gettext_wrap: false; //if Pomo can be found, alias it
  if(!gettext_wrap){
    throw new "Pomo can't be found";
  }

  return gettext_wrap;
})();

Non-evident note: Pomo by default provides a kind of object that can be used as a string, but can be coerced into returning strings by setting Pomo.returnStrings = true