Add a callback to Firebase Login Function

Question

I am fairly new to React and the use of Firebase. Right now I have a Firebase.js file where I have stored and exported all of my functions and consts. This is what it looks like:

export const auth = firebase.auth();

export function performLogin(email, password) {
  auth.signInWithEmailAndPassword(email, password).then(function(data) {
    //Works
  }).catch(function(error) {
    //Does not work
  });
}

So, I have this login.js that I am calling performLogin from, and I was wondering what would be the best way of doing this? How can I create a callback, or at least read any kind of return message? This is how I call performLogin:

clickLogin(e){

    e.preventDefault();
    performLogin(this.state.email, this.state.password);
}

And this works, as the console output tells me if the login was successful or not. However, I want to be able to use this function in order to retrieve the login status, and then determine wether or not I should prompt an error message or push the user to the admin dashboard. How would I do this?

Is it possible to call performLogin like this?

performLogin(this.state.email,this.state.password,(callback)){
 if (callback == true) { //Success } else { //Error }
}

Answer 1

Take a look at the function onAuthStateChanged from "firebase/auth" package.

Here is a link to the docs: https://firebase.google.com/docs/auth/web/manage-users