auth.js

auth.onAuthStateChanged(user => {

    getTodos();
    setupUI(user);
})

const logout = document.querySelector('#logout');

//Logout event
logout.addEventListener('click', e => {
    e.preventDefault();
    auth.signOut();
})

//Login authentification
const loginForm = document.querySelector('#login-form');

loginForm.addEventListener('submit', e => {
    e.preventDefault();

    const email = loginForm['login-email'].value;
    const password = loginForm['login-password'].value;

    auth.signInWithEmailAndPassword(email, password).then(() => {

        const modal = document.querySelector('#modal-login');
        M.Modal.getInstance(modal).close();
        loginForm.querySelector('.error').innerHTML = '';
        loginForm.reset();

    }).catch(err => {
        loginForm.querySelector('.error').innerHTML = err.message;
    })
})

//Signup comprobation and post
const signupForm = document.querySelector('#signup-form');
 signupForm.addEventListener('submit', e => {
    e.preventDefault();
    const email = signupForm['signup-email'].value;
    const password = signupForm['signup-password'].value;
    auth.createUserWithEmailAndPassword(email, password).then(() => {
        const modal = document.querySelector('#modal-signup');
        M.Modal.getInstance(modal).close();
        signupForm.querySelector('.error').innerHTML = '';
        signupForm.reset();

    }).catch(err => {
        signupForm.querySelector('.error').innerHTML = err.message;
    })
})