Sending Firebase Notifications with FCM and Node.js: A Step-by-Step Guide

To send Firebase Cloud Messaging (FCM) notifications using Node.js, you can use the Firebase Admin SDK, which provides a set of Node.js libraries for interacting with Firebase services. Here are the steps you can follow:

Set up your Firebase project and obtain your Firebase Admin SDK credentials. You can find detailed instructions in the Firebase documentation.
Install the Firebase Admin SDK by running the following command in your Node.js project directory:
```
 npm install firebase-admin
```
Initialize the Firebase Admin SDK with your credentials by including the following code at the top of your Node.js file:
```
 const admin = require('firebase-admin');

 const serviceAccount = require('./path/to/serviceAccountKey.json');

 admin.initializeApp({
   credential: admin.credential.cert(serviceAccount),
 });
```
Replace './path/to/serviceAccountKey.json' with the path to your Firebase Admin SDK credentials file.
Use the admin.messaging() method to create an instance of the Firebase Cloud Messaging service. You can use this instance to send notifications. For example:
```
 const messaging = admin.messaging();
```

To send a notification, you can use the messaging.send() method, passing in a message object that contains the notification data. For example:

 const message = {
   notification: {
     title: 'New message',
     body: 'You have a new message from John',
   },
   token: 'device_token',
 };

 messaging.send(message)
   .then((response) => {
     console.log('Successfully sent message:', response);
   })
   .catch((error) => {
     console.log('Error sending message:', error);
   });

Replace 'device_token' with the registration token of the device you want to send the notification to.

These are the basic steps for sending FCM notifications using Node.js and the Firebase Admin SDK. You can find more information and examples in the Firebase documentation.