JS/Firebase - messaging.onBackgroundMessage 不是 function

Question

这是我的整个代码：

import { initializeApp } from "https://www.gstatic.com/firebasejs/9.16.0/firebase-app.js";
import { getMessaging, getToken } from "https://www.gstatic.com/firebasejs/9.16.0/firebase-messaging.js";
//This data is filled correctly just clearing it here for the question
const firebaseConfig = {
    apiKey: "",
    authDomain: "",
    projectId: "t",
    storageBucket: "",
    messagingSenderId: "",
    appId: "",
    measurementId: ""
};

// Initialize Firebase
const bbFirebase = initializeApp(firebaseConfig);
const messaging = getMessaging();
// Add the public key generated from the console here.
getToken(messaging, { vapidKey: 'I_HAVE_PLACED_VALID_KEY_HERE' }).then((currentToken) => {
    if (currentToken) {
        console.log("TOKEN: " + currentToken);
    } else {
        // Show permission request UI
        console.log('No registration token available. Request permission to generate one.');
        // ...
    }
}).catch((err) => {
    console.log('An error occurred while retrieving token. ', err);
    // ...
});

messaging.onBackgroundMessage((payload) => {
    console.log('[firebase-messaging-sw.js] Received background message ', payload);
    // Customize notification here
    const notificationTitle = payload.notification.title;
    const notificationOptions = {
        body:  payload.notification.body,
        icon: '/firebase-logo.png'
    };

    self.registration.showNotification(notificationTitle,
        notificationOptions);
});
function requestPermission() {
    console.log('Requesting permission...');
    Notification.requestPermission().then((permission) => {
        if (permission === 'granted') {
            console.log('Notification permission granted.');
            // TODO(developer): Retrieve a registration token for use with FCM.
            // In many cases once an app has been granted notification permission,
            // it should update its UI reflecting this.
            resetUI();
        } else {
            console.log('Unable to get permission to notify.');
        }
    });
}

所以当我执行这段代码时，我可以生成一个令牌。 我清楚地看到令牌，那里一切都很好。 但是我有这个错误：

未捕获的类型错误：messaging.onBackgroundMessage 不是 function at firebase.js:31:11

知道为什么我会出现这个错误，我怎样才能至少console.log()打印传入的通知？

Answer 1

onBackgroundMessage()是顶级 function，就像文档中提到的从firebase/messaging/sw导入的新功能语法中的 getToken( getToken()一样。

import { getMessaging, onMessage } from 'firebase/messaging'
import { onBackgroundMessage } from 'firebase/messaging/sw'

onBackgroundMessage(messaging, (payload) => {
  // ...
})