如何使用 JS 文件进行 Firebase 身份验证？

createUserWithEmailAndPassword 未定义

如何在 auth.js 文件中访问 index.html 中初始化的 auth 对象？我应该将其作为参数传递吗？还是有更好的方法在模块化 JavaScript 设置中管理 Firebase 身份验证？如能提供任何指导，我将不胜感激！

<form id="signup-form">
    <div class="input-field">
        <input type="email" id="signup-email" required />
        <label for="signup-email">Email address</label>
    </div>
    <div class="input-field">
        <input type="password" id="signup-password" required />
        <label for="signup-password">Password</label>
    </div>
    <button type="submit">Sign Up</button>
</form>

<script type="module">
    import { initializeApp } from "https://www.gstatic.com/firebasejs/10.14.1/firebase-app.js";
    import { getAuth } from "https://www.gstatic.com/firebasejs/10.14.1/firebase-auth.js";

    const firebaseConfig = {
        apiKey: "API_KEY",
        authDomain: "AUTH_DOMAIN",
        projectId: "PROJECT_ID",
        storageBucket: "STORAGE_BUCKET",
        messagingSenderId: "MESSAGING_SENDER_ID",
        appId: "APP_ID",
        measurementId: "MEASUREMENT_ID"
    };

    const app = initializeApp(firebaseConfig);
    const auth = getAuth(app);  // Initializes the auth service
</script>
<script src="scripts/auth.js"></script>

const signupForm = document.querySelector('#signup-form');

signupForm.addEventListener('submit', (e) => {
    e.preventDefault();
    const email = signupForm['signup-email'].value;
    const password = signupForm['signup-password'].value;

    createUserWithEmailAndPassword(auth, email, password).then((cred) => {
        console.log(cred);
    }).catch((error) => {
        console.error("Error creating user:", error);
    });
});