i made a signup page where u put infos and it saves in database , im using firebase in this
this is my HTML code for the button :

<!-- Signup Popup -->
    <div class="popup" id="signup-popup">
        <div class="popup__content">
            <h2>Signup</h2>
            <form>
                <input type="text" placeholder="Username">
                <input type="email" placeholder="Email">
                <input type="password" placeholder="Password">
                <button type="submit" class="button" id="signup">Signup</button>
            </form>
        </div>
    </div>

and this is the firebase :

// Initialize Firebase
const app = initializeApp(firebaseConfig);
const analytics = getAnalytics(app);

//inputs
const email = document.getElementById('email').value;
const password = document.getElementById('password').value;

//submit button
const submit = document.getElementById('signup');
submit.addEventListener("click", function(event){
  event.preventDefault()
  alert(5)
})

i tried to change the id in const submit = document.getElementById('signup') to signup-popup