如何修正参考错误:当所有 SDK 都在 HTML 文件中时，系统并未定义 Firebase

Question

我正在尝试设计一个具有使用Firebase的登录表单的网站。

我按照文档(https://firebase.google.com/docs/web/setup?authuser=0(将Firebase所需的所有JS软件开发工具包以及Firebase-Auth SDK添加到我的HTML文件中。我还有一个用于 onclick 事件等的 JS 文件，我想在其中使用 firebase 库中的方法。

<div class="loginContainer">
    <div class="card"></div>
    <div class="card">
        <h1 class="title">Login</h1>
        <form>
            <div class="input-container">
                <input type="text" id="txtEmail" required="required" />
                <label for="email_field">E-Mail</label>
                <div class="bar"></div>
            </div>
            <div class="input-container">
                <input type="password" id="txtPassword" required="required" />
                <label for="password_field">Password</label>
                <div class="bar"></div>
            </div>
            <div class="button-container">
                <button onClick="login();" id="btnLogin"><span>Go</span></button>
            </div>
        </form>
    </div>
</div>
<script src="assets/js/login.js"></script>
<!-- The core Firebase JS SDK is always required and must be listed first -->
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script src="https://www.gstatic.com/firebasejs/6.1.1/firebase-app.js"></script>
<!-- TODO: Add SDKs for Firebase products that you want to use -->
<!-- Insert these scripts at the bottom of the HTML, but before you use any Firebase services -->
<!-- Add Firebase products that you want to use -->
<script src="https://www.gstatic.com/firebasejs/6.2.0/firebase-auth.js"></script>
<script src="https://www.gstatic.com/firebasejs/6.2.0/firebase-firestore.js"></script>
<script>
    // Your web app's Firebase configuration
    var firebaseConfig = {
        (the config from my Firebase console)
    };
    // Initialize Firebase
    firebase.initializeApp(firebaseConfig);
</script>

const auth = firebase.auth();

我希望JS文件能够识别auth((方法，但我得到的只是控制台中的"未捕获的引用错误：登录时未定义firebase.js：2"。

Answer 1

在

Firebase SDK 脚本之后添加对 js 文件的引用：

//firebase sdk
<script src="https://www.gstatic.com/firebasejs/6.2.0/firebase-auth.js"></script> 
<script src="assets/js/login.js"></script>