docs: function getFileTypeReg(type) {
    var map = [], ext = her.config.get('project.fileType.' + type);
    if (type === 'text') {
      map = TEXT_FILE_EXTS;
    } else if (type === 'image') {
      map = IMAGE_FILE_EXTS;
    } else {
      throw new Error('invalid file type [' + type + ']');
    }
    if (ext && ext.length) {
      if (typeof ext === 'string') {
        ext = ext.split(/\s*,\s*/);
      }
      map = map.concat(ext);
    }
    map = map.join('|');
    return new RegExp('\\.(?:' + map + ')$', 'i');
  }