CODE EXAMPLE FOR JAVASCRIPT

subdomain react app

let host = window.location.host;
let protocol = window.location.protocol;
let parts = host.split(".");
let subdomain = "";
// If we get more than 3 parts, then we have a subdomain
// INFO: This could be 4, if you have a co.uk TLD or something like that.
if (parts.length >= 3) {
  subdomain = parts[0];
  // Remove the subdomain from the parts list
  parts.splice(0, 1);
  // Set the location to the new url
  window.location = protocol + "//" + parts.join(".") + "/" + subdomain;
}