bring cookies from the same domain from React?

Question

try this

https://example.com(auth server) -redirect(cookie[token: "abcdef")-> https://dev.example.com(my react admin)

When redirect it to dev.example.com, I put the cookie in, and I want to get the cookie CheckAuth in AuthProvider.

I'd like to get a request from the browser from CheckAuth and get the cookies in it.

const authProvider: AuthProvider = {
    login: ({ username }) => {
        localStorage.setItem('username', username);
        // accept all username/password combinations
        return Promise.resolve();
    },
    logout: () => {
        localStorage.removeItem('username');
        return Promise.resolve();
    },
    checkError: () => Promise.resolve(),
   checkAuth: (req) => {

        const cookies = new Cookies(req.headers.cookie); <<-- what should i do??
        console.log(cookies);

        // return   localStorage.getItem('username') ? Promise.resolve() : Promise.reject()
        // return Promise.resolve({ redirectTo: 'http://heimdall-local.dev.daumkakao.io' })
        return Promise.resolve();
    },
    getPermissions: () => Promise.reject('Unknown method'),
    getIdentity: () =>
        Promise.resolve({
            id: 'user',
            fullName: 'Jane Doe',
            avatar:
      
        }),
};