code: function getFileExtension(fullPath) {
          var baseName = getBaseName(fullPath),
              idx      = baseName.lastIndexOf(".");
  
          if (idx === -1) {
              return "";
          }
  
          return baseName.substr(idx + 1);
      }
docs: Get the file extension (excluding ".") given a path OR a bare filename.
  Returns "" for names with no extension. If the name starts with ".", the
  full remaining text is considered the extension.
  
  @param {string} fullPath full path to a file or directory
  @return {string} Returns the extension of a filename or empty string if
  the argument is a directory or a filename with no extension