Express server to send push notifications using weboush

pushNotificationsExpressserver.ts

import * as express from 'express';
import {Application} from "express";
const webpush = require('web-push');
const bodyParser = require('body-parser');
const cors = require('cors');

const vapidKeys = {
    "publicKey":...,
    "privateKey":...
}


webpush.setVapidDetails(
    'mailto:xxx@xxx.xxx',
    vapidKeys.publicKey,
    vapidKeys.privateKey
);

const USER_SUBSCRIPTIONS = [];




const app: Application = express();


app.use(bodyParser.json());
app.use(cors());


app.route('/')
    .post((req, res) =>  {
        // for personalization
        const { sub, id, email } = req.body;
    
        console.log('Received Subscription on the server from user : ', email);
        // Perisst this
        USER_SUBSCRIPTIONS.push(sub);
    
        res.status(200).json({message: "Subscription added successfully."});
    });

app.route('/subs').get((req, res) => {
    res.status(200).json(USER_SUBSCRIPTIONS);
})

app.route('/send')
    .post((req, res) => {

        console.log('Total subscriptions', USER_SUBSCRIPTIONS.length);
    
        // sample notification payload
        const notificationPayload = generateNotification('Title','Summary', 
        'http://someurl.to.link');
    
        // only send to interested users
        Promise.all(USER_SUBSCRIPTIONS.map(sub => webpush.sendNotification(
            sub, JSON.stringify(notificationPayload) )))
            .then(() => res.status(200).json({message: 'Newsletter sent successfully.'}))
            .catch(err => {
                console.error("Error sending notification, reason: ", err);
                res.sendStatus(500);
            });
    });



// launch an HTTP Server
const httpServer = app.listen(3000, () => {
    console.log("HTTP Server running at http://localhost:3000");
});

// The backend should already know the User id & details

const generateNotification = (title: string = 'Defult Title', body: string, url: string = "Default Url") => {
    return {
        "notification": {
            title, body, icon: "assets/favicons/quabb-default.ico", vibrate: [100, 50, 100],
            data: {
                "dateOfArrival": Date.now(),
                "primaryKey": 1,
                actionUrl: url
            },
            endpoint: url
        }
    }
}