Javascript - 通过Firebase初始化Cloud Firestore时出错

我正在将一个简单的html/javascript项目从firebase实时数据库迁移到cloud firestore。我遵循quickstart并添加了firebase-firestore的库 - 但是当我尝试初始化firestore时，我得到'Uncaught TypeError：firebase.firestore不是函数'。快速启动中提到：Javascript - 通过Firebase初始化Cloud Firestore时出错

const firebase = require("firebase"); 
// Required for side-effects 
require("firebase/firestore");

..但我认为，只有当我使用NPN获得库和不适用的？

我错过了什么？

的index.html

<head> 
<script src="https://www.gstatic.com/firebasejs/4.5.1/firebase.js"></script> 
<script src="https://www.gstatic.com/firebasejs/4.5.1/firebase-firestore.js"></script> 
<script src="./app.js" type="text/javascript"></script>

app.js

(function() 

    {var config = { 
    apiKey: "...", 
    authDomain: "...", 
    databaseURL: "...", 
    projectId: "...", 
    storageBucket: "...", 
    messagingSenderId: "..." 
    }; 

firebase.initializeApp(config); 

var oldDB = firebase.database(); <-- THIS WORKS 
// Initialize Cloud Firestore through Firebase 
var newDB = firebase.firestore(); <-- 'Uncaught TypeError: firebase.firestore is not a function'

来源

2017-10-20 Chris Pawley