code: function fileToURL(output, filePath) {
      var options = output.getOptions();
      var directoryIndex = options.get('directoryIndex');
  
      filePath = fileToOutput(output, filePath);
  
      if (directoryIndex && path.basename(filePath) == 'index.html') {
          filePath = path.dirname(filePath) + '/';
      }
  
      return LocationUtils.normalize(filePath);
  }
docs: Convert a filePath (absolute) to an url (without hostname).
  It returns an absolute path.
  
  "README.md" -> "/"
  "test/hello.md" -> "test/hello.html"
  "test/README.md" -> "test/"
  
  @param {Output} output
  @param {String} filePath
  @return {String}