Google App Script to reverse a url

reverse-url.gs

/**
 * Reverses the input url.
 * 
 * EG: if the url is www.google.com, the result will be com.google.www - this is useful for sorting a sheet
 *
 * @param {string} input The url to reverse.
 * @return The url reversed.
 * @customfunction
 */
function REVERSEURL(string) {
  if (typeof string != 'string') {
    return null;
  }
  return string.split('.').reverse().join('.');
}