code: function pathParser(root, extname, subPath, paths) {
    var dirPath = path.resolve(subPath || root);
    var files;
    paths = paths || {};
  
    try {
      files = fs.readdirSync(dirPath);
    } catch(e) {
      files = [];
    }
    files.forEach(function(file) {
      file = path.join(dirPath, '/', file);
      if (fs.statSync(file).isFile()) {
        if (~extname.split('|').indexOf(path.extname(file).substr(1))) {
          var rootPath = '^' + path.join(path.resolve(root), '/');
          rootPath = rootPath.replace(/\\/g, '\\\\') + '(.*)\.(' + extname + ')$';
          paths[file.match(new RegExp(rootPath))[1].toLowerCase()] = file;
        }
      } else if (fs.statSync(file).isDirectory()) {
        pathParser(root, extname, file, paths);
      }
    });
    return paths;
  }
docs: to parse the paths of files
  @param  {String} root    root path
  @param  {String} subPath sub dir path
  @param  {Object} paths   dictionary of the paths
  @return {Object}         dictionary of the paths
  @api private