_path.walk.js

path.walk = function (start, callback) {
  fs.stat(start, function (err, stat) {
    if (stat.isDirectory()) {

      fs.readdir(start, function (err, files) {
        var coll = files.reduce(function (acc, i) {
          var abspath = path.join(start, i);

          if (fs.statSync(abspath).isDirectory()) {
            path.walk(abspath, callback);
            acc.dirs.push(abspath);
          } else {
            acc.names.push(abspath);
          }

          return acc;
        }, {"names": [], "dirs": []});

        callback(start, coll.dirs, coll.names);
      });
    } else {
      return null;
    }
  });
};

path.walkSync = function (start, callback) {
  var stat = fs.statSync(start);
  if (stat.isDirectory()) {
    var coll = fs.readdirSync(start).reduce(function (acc, i) {
      var abspath = path.join(start, i);

      if (fs.statSync(abspath).isDirectory()) {
        path.walk(abspath, callback);
        acc.dirs.push(abspath);
      } else {
        acc.names.push(abspath);
      }

      return acc;
    }, {"names": [], "dirs": []});

    return callback(start, coll.dirs, coll.names);
  } else {
    return null;
  }
}