How to integrate FCM in node.js for push notifications?

Question

I want to add the push notification thing using FCM in Node.js .For that I tried this

and this and also this

My nodejs code

var FCM = require('fcm-node');

var serverkey = 'SERVERKEY';  
var fcm = new FCM(serverkey);
var message = {  
			to : req.body.userToken,
			collapse_key : 'XXX',
			data : {
					my_key: 'my value', contents: "abcv/"
			},
			notification : {
					title : 'Title of the notification',
					body : 'Body of the notification'
			}
	};

fcm.send(message, function(err,response){  
if(err) {
	console.log(message);
       console.log("Something has gone wrong !");
 } else {
     console.log("Successfully sent with resposne :",response);
   }
});	

Whenever I try to run this code and start my server,I get this error in the console always.

 /var/www/html/chatApp/node_modules/fcm-node/lib/fcm.js:10
 function FCM(accountKey, proxy_url=null) {
                              ^
 SyntaxError: Unexpected token =
at Module._compile (module.js:439:25)
at Object.Module._extensions..js (module.js:474:10)
at Module.load (module.js:356:32)
at Function.Module._load (module.js:312:12)
at Module.require (module.js:364:17)
at require (module.js:380:17)
at Object.<anonymous> (/var/www/html/chatApp/node_modules/fcm-node/index.js:1:80)
at Module._compile (module.js:456:26)
at Object.Module._extensions..js (module.js:474:10)
at Module.load (module.js:356:32)

Can anybody please explain what I'm doing wrong?

Solution

I used the firebase-admin package for sending the notifications (https://firebase.google.com/docs/cloud-messaging/admin/send-messages)

var admin = require("firebase-admin");

var serviceAccount = require("./firebase-adminSDK.json");

admin.initializeApp({
    credential: admin.credential.cert(serviceAccount),
});
const messaging = admin.messaging()
    var payload = {
        notification: {
            title: "This is a Notification",
            body: "This is the body of the notification message."
        },
        topic: 'topic'
        };


    messaging.send(payload)
    .then((result) => {
        console.log(result)
    })

The firebase-adminSDK.json can be download following the steps in https://firebase.google.com/docs/admin/setup#add_firebase_to_your_app

This code will send a notification to the topic 'topic', however, the firebase-admin package allows sending notifications to a specific device.