Firebase cross domain authentication using only frontend

Question

“Cross domain authentication” and “subdomain authentication” such questions are old and repeatedly asking questions in stack overflow. However all of the things are integrating using backend application but I need authenticate to two or more sub-domain or cross domain authentication using only front-end application and firebase.

If it possible by using JavaScript it helps to all front-end developer.

If it possible to do please help me or redirect me right ref

I have already tried as below

Form Main Domain http://localhost:3000 : Authenticated main domain use exist Signed In

() => {
      const { getAuth, onAuthStateChanged } = require('firebase/auth')
      const auth = getAuth(app);
      onAuthStateChanged(auth, (UserCredential: any) => {
        if (UserCredential) {
          let refreshToken = UserCredential.stsTokenManager.refreshToken
          console.log(refreshToken)
          window.location.href = `http://localhost:3001/Auth?id=${refreshToken}`

        } else { console.log("User is signed out") }
      });
  

For Sub-Domain http://localhost:3001 : Required to Authenticated

var url_string = window.location.href
    var url = new URL(url_string);
    var token_From_url = url.searchParams.get("id");
const auth = getAuth(app);
    signInWithCustomToken(auth, token_From_url)
        .then((userCredential) => {
            let j = userCredential.operationType
            // Signed in
            const user = userCredential.user
        })
        .catch((error) => {
            const errorCode = error.code;
            const errorMessage = error.message;
            console.log("errorCode :", errorCode);
            console.log("errorMessage :", errorMessage)
        });
}

I got error

errorCode : auth/invalid-custom-token Auth.tsx:23 errorMessage :

Firebase: Invalid assertion format. 3 dot separated segments required. (auth/invalid-custom-token). Auth.tsx:22