A base for a node js jekyll gettext preprocessor - requires docs/nl to exist and expects the first user visible string in api.md to be wrapped in a {%t %} tag.

api.pot

msgid ""
msgstr ""

msgid "Most of the PouchDB API is exposed as `fun(arg, [options], [callback])` where both the options and the callback are optional. Callbacks use the `function(err, result)` idiom where the first argument will be undefined unless there is an error, and the second argument holds the result."
msgstr ""

jekyll-node-gettext.js

var fs = require('fs');
var PO = require('pofile');

fs.readFile('docs/api.md', {encoding: 'UTF-8'}, function (err, content) {
  // build api.pot based on docs/api.md
  buildPOTFile(content, 'api.pot');

  // use nl.po to create a docs/nl/api.md
  buildTranslatedMarkdown(content, 'nl.po', 'docs/nl/api.md');
});

function buildPOTFile(content, filename) {
  var pot = new PO();
  findTranslationsInMarkdown(content, function (english) {
    var item = new PO.Item();
    item.msgid = english;
    pot.items.push(item);
  });
  pot.save(filename);
}

function buildTranslatedMarkdown(content, poName, mdName) {
  PO.load(poName, function (err, po) {
    var newContent = findAndReplaceTranslationsInMarkdown(content, function (english) {
      var result;
      for (var i = 0; i < po.items.length; i += 1) {
        var item = po.items[i];
        if (item.msgid && item.msgid.trim() === english && item.msgstr) {
          return item.msgstr[0].trim();
        }
      }
      return english;
    });
    fs.writeFile(mdName, newContent, {encoding: 'UTF-8'});
  });
}

var re = /{%t (.+) %}/g;
function findTranslationsInMarkdown(content, onFound) {
  var match;
  while (match = re.exec(content)) {
    var text = match[1].trim();
    var start = match.index;
    var length = match[0].length;

    onFound(text, start, length);
  }
}

function findAndReplaceTranslationsInMarkdown(content, replace) {
  var newContent = "";
  var lastMatchEnd = 0;
  findTranslationsInMarkdown(content, function (text, start, length) {
    newContent += content.slice(lastMatchEnd, start);
    newContent += replace(text);
    lastMatchEnd += start + length;
  });
  newContent += content.slice(lastMatchEnd);
  return newContent;
}

nl.po

msgid ""
msgstr ""
"Project-Id-Version: \n"
"POT-Creation-Date: \n"
"PO-Revision-Date: \n"
"Last-Translator: Marten de Vries <marten94@gmail.com>\n"
"Language-Team: \n"
"MIME-Version: 1.0\n"
"Content-Type: text/plain; charset=iso-8859-1\n"
"Content-Transfer-Encoding: 8bit\n"
"X-Generator: Poedit 1.5.4\n"

msgid ""
"Most of the PouchDB API is exposed as `fun(arg, [options], [callback])` "
"where both the options and the callback are optional. Callbacks use the "
"`function(err, result)` idiom where the first argument will be undefined "
"unless there is an error, and the second argument holds the result. "
msgstr ""
"Het grootste deel van de PouchDB API wordt beschikbaar gemaakt in het "
"formaat `fun(arg, [options], [callback])` waarbij zowel options als callback "
"optioneel zijn. Callsbacks gebruiken het `function (err, result)`-formaat "
"waarbij het eerste argument undefined zal zijn tenzij er een fout optreedt, "
"en het tweede argument het resultaat bevat."