useFakeAuth React Hook

use-fake-auth-hook.js

// Current auth status
let currentAuth = false;

// Holds setAuth for every instance of hook
const authSetters = new Set();

function useFakeAuth() {
  // Auth state and setter
  const [auth, setAuth] = useState(currentAuth);

  // Add setAuth to authSetters
  useEffect(
    () => {
      authSetters.add(setAuth);
      return () => authSetters.delete(setAuth);
    },
    [setAuth]
  );

  // Fake async API call to auth or de-auth
  // In real life you'd probably pass in an email/pass
  // And have onSuccess and onError instead of a callback arg
  const setAuthApi = (newAuth, cb) => {
    setTimeout(() => {
      // Update current auth status
      currentAuth = newAuth;
      // Call setAuth for every instance of hook
      authSetters.forEach(setter => setter(newAuth));
      cb && cb();
    }, 100);
  };

  const signin = cb => setAuthApi(true, cb);
  const signout = cb => setAuthApi(false, cb);

  return [auth, signin, signout];
}