get root domain from URL (JavaScript) for setting `Domain` in `Cookie` header

get-root-origin.js

const getOrigin = str => str.replace(/.*\/\//, '').replace(/:.+/, '').replace(/\/.+/, '');

const getOriginRoot = (str) => {
  const originFull = getOrigin(str);
  if (!originFull.includes('.')) {
    return str;
  }
  const originFullChunks = originFull.split('.');
  const originRoot = originFullChunks.slice(originFullChunks.length - 2, originFullChunks.length).join('.');
  return originRoot;
};