code: function buildUrlSearch(query) {
  
    function buildParam(key) {
      let value = query[key];
      if (value === null || value === undefined) value = '';
      else value = encodeURIComponent(value);
      return `${key}=${value}`;
    }
  
    return keys(query) . map(buildParam) . join('&');
  }
docs: Build a search string (with no ?) from an object.