get-apex-domain/src/index.js

Returns the apex domain (aka base, bare, naked, root apex, or zone apex domain) of the current web page without the use of a public suffix list. The apex domain is also the top-most domain that allows for setting cookies.

import getApexDomain from "./getApexDomain";
import cookieJar from "./cookieJar";

let apexDomain;
let apexDomainRetrieved;

export default () => {
  if (!apexDomainRetrieved) {
    apexDomain = getApexDomain(window, cookieJar);
    apexDomainRetrieved = true;
  }

  return apexDomain;
};