facebook_expo.js

export const facebookLogin = async () => {
  try {
    const { type, token } = await Facebook.logInWithReadPermissionsAsync('<YOUR APP ID>', {
      permissions: ['public_profile', 'email', 'user_birthday'],
      behavior: 'native',
    });
    if (type === 'success') {
      // Get the user's name using Facebook's Graph API
      
      const credential = firebase.auth.FacebookAuthProvider.credential(token)
      firebase.auth().signInWithCredential(credential).catch((error) => {
        console.log(error)
      })
      
      const uid = firebase.auth().currentUser.uid; //this would return you the user id
      //then you can perform other stuff like, saving their names to an object ect...
      
      return await response.json();
    }
    // type === 'cancel'
    return 'cancel';
  } catch ({ message }) {
    return console.error(`Facebook Login Error: ${message}`);
  }
};

thanks bro, it works