Firebase Detecting if user exists

Question

How Can I Check user exists in Firebase auth in Signup Button via react native?

This is my Login Page Code:

export de         


        

Answer 1

Here's how to use the fetchSignInMethodsForEmail API. It returns an array. If the array is empty, it means the user has never signed up/signed in to your app with the sign in methods you have used in your app.

This is an example with Google signin.

firebase
    .auth()
    .signInWithPopup(provider)
    .then((result) => {
        let token = result.credential.accessToken;
        let user = result.user;

        firebase
            .auth()
            .fetchSignInMethodsForEmail(user.email)
            .then((result) => {
                console.log('result', result);
            });
        })
        .catch((error) => {
            // Handle Errors here.
        }