Web-push Notification using React and Node js

I will share my code here for better understanding the core concept.

public/custom-sw.js

console.log("Service Worker Loaded...");
self.addEventListener('push', event => {
  const data = event.data.json()
  console.log('New notification', data)
  event.waitUntil(
    self.registration.showNotification(data.title, {
      body:data.description,
      icon:data.icon
    })
  );
})

src/serviceWorker.js

// This optional code is used to register a service worker.
// register() is not called by default.

// This lets the app load faster on subsequent visits in production, and gives
// it offline capabilities. However, it also means that developers (and users)
// will only see deployed updates on subsequent visits to a page, after all the
// existing tabs open on the page have been closed, since previously cached
// resources are updated in the background.

// To learn more about the benefits of this model and instructions on how to
// opt-in, read https://bit.ly/CRA-PWA

const isLocalhost = Boolean(
    window.location.hostname === 'localhost' ||
      // [::1] is the IPv6 localhost address.
      window.location.hostname === '[::1]' ||
      // 127.0.0.1/8 is considered localhost for IPv4.
      window.location.hostname.match(
        /^127(?:\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}$/
      )
  );

  export function register(config) {
    if ('serviceWorker' in navigator) {
      // The URL constructor is available in all browsers that support SW.
      const publicUrl = new URL(process.env.PUBLIC_URL, window.location.href);
      if (publicUrl.origin !== window.location.origin) {
        // Our service worker won't work if PUBLIC_URL is on a different origin
        // from what our page is served on. This might happen if a CDN is used to
        // serve assets; see https://github.com/facebook/create-react-app/issues/2374
        return;
      }

      window.addEventListener('load', () => {
        const swFileName = process.env.NODE_ENV === 'production' ? 'service-worker.js' : 'custom-sw.js'
        const swUrl = `${process.env.PUBLIC_URL}/${swFileName}`;

        if (isLocalhost) {
          // This is running on localhost. Let's check if a service worker still exists or not.
          checkValidServiceWorker(swUrl, config);

          // Add some additional logging to localhost, pointing developers to the
          // service worker/PWA documentation.
          navigator.serviceWorker.ready.then(() => {
            console.log(
              'This web app is being served cache-first by a service ' +
                'worker. To learn more, visit https://bit.ly/CRA-PWA'
            );
          });
        } else {
          // Is not localhost. Just register service worker
          registerValidSW(swUrl, config);
        }
      });
    }
  }

  function registerValidSW(swUrl, config) {
    navigator.serviceWorker
      .register(swUrl)
      .then(registration => {
        registration.onupdatefound = () => {
          const installingWorker = registration.installing;
          if (installingWorker == null) {
            return;
          }
          installingWorker.onstatechange = () => {
            if (installingWorker.state === 'installed') {
              if (navigator.serviceWorker.controller) {
                // At this point, the updated precached content has been fetched,
                // but the previous service worker will still serve the older
                // content until all client tabs are closed.
                console.log(
                  'New content is available and will be used when all ' +
                    'tabs for this page are closed. See https://bit.ly/CRA-PWA.'
                );

                // Execute callback
                if (config && config.onUpdate) {
                  config.onUpdate(registration);
                }
              } else {
                // At this point, everything has been precached.
                // It's the perfect time to display a
                // "Content is cached for offline use." message.
                console.log('Content is cached for offline use.');

                // Execute callback
                if (config && config.onSuccess) {
                  config.onSuccess(registration);
                }
              }
            }
          };
        };
      })
      .catch(error => {
        console.error('Error during service worker registration:', error);
      });
  }

  function checkValidServiceWorker(swUrl, config) {
    // Check if the service worker can be found. If it can't reload the page.
    fetch(swUrl)
      .then(response => {
        // Ensure service worker exists, and that we really are getting a JS file.
        const contentType = response.headers.get('content-type');
        if (
          response.status === 404 ||
          (contentType != null && contentType.indexOf('javascript') === -1)
        ) {
          // No service worker found. Probably a different app. Reload the page.
          navigator.serviceWorker.ready.then(registration => {
            registration.unregister().then(() => {
              window.location.reload();
            });
          });
        } else {
          // Service worker found. Proceed as normal.
          registerValidSW(swUrl, config);
        }
      })
      .catch(() => {
        console.log(
          'No internet connection found. App is running in offline mode.'
        );
      });
  }

  export function unregister() {
    if ('serviceWorker' in navigator) {
      navigator.serviceWorker.ready.then(registration => {
        registration.unregister();
      });
    }
  }

src/subscription.js

const convertedVapidKey = urlBase64ToUint8Array("YOUR_PUBLIC VAPID_KEY")

function urlBase64ToUint8Array(base64String) {
  const padding = "=".repeat((4 - base64String.length % 4) % 4)
  // eslint-disable-next-line
  const base64 = (base64String + padding).replace(/\-/g, "+").replace(/_/g, "/")

  const rawData = window.atob(base64)
  const outputArray = new Uint8Array(rawData.length)

  for (let i = 0; i < rawData.length; ++i) {
    outputArray[i] = rawData.charCodeAt(i)
  }
  return outputArray
}

function sendSubscription(subscription) {
  return fetch(`/notifications/subscribe`, {
    method: 'POST',
    body: JSON.stringify({
      subscription:subscription,
      title:"Notified by Precision Ordance",
      description:"someone buy a product",
      icon:"https://ichef.bbci.co.uk/news/976/cpsprodpb/9A50/production/_118740593_gettyimages-1231144196.jpg"
    }),
    headers: {
      'Content-Type': 'application/json'
    }
  })
}
//conditional render
let clicked = true

export function subscribeUser() {
  if(clicked) {
  if ('serviceWorker' in navigator) {
    navigator.serviceWorker.ready.then(function(registration) {
      if (!registration.pushManager) {
        console.log('Push manager unavailable.')
        return
      }

      registration.pushManager.getSubscription().then(function(existedSubscription) {
        if (existedSubscription === null) {
          console.log('No subscription detected, make a request.')
          registration.pushManager.subscribe({
            applicationServerKey: convertedVapidKey,
            userVisibleOnly: true,
          }).then(function(newSubscription) {
            console.log('New subscription added.',newSubscription)
            sendSubscription(newSubscription)
          }).catch(function(e) {
            if (Notification.permission !== 'granted') {
              console.log('Permission was not granted.')
            } else {
              console.error('An error ocurred during the subscription process.', e)
            }
          })
        } else {
          console.log('Existed subscription detected.')
          sendSubscription(existedSubscription)
        }
      })
    })
      .catch(function(e) {
        console.error('An error ocurred during Service Worker registration.', e)
      })
  }
}else{
console.log('Can not reachable to the service worker');
}}

src/App.JS

import './App.css';
import { subscribeUser } from './subscription';
function App() {
  return (
    <div className="App">
      <header className="App-header">
        <button onClick={subscribeUser}>Click Here</button>
        <p>
          Edit <code>src/App.js</code> and save to reload.
        </p>
        <a
          className="App-link"
          href="https://reactjs.org"
          target="_blank"
          rel="noopener noreferrer"
        >
          Learn React
        </a>
      </header>
    </div>
  );
}

export default App;

src/index.js

import React from 'react';
import ReactDOM from 'react-dom';
import App from './App';
import './index.css';
import * as serviceWorker from './serviceWorker';
import { subscribeUser } from './subscription';

ReactDOM.render(<App />, document.getElementById('root'));
serviceWorker.register();

subscribeUser()

src/package.json()
just install one package-->npm i cra-append-sw

"dependencies": {
    "@testing-library/jest-dom": "^5.15.0",
    "@testing-library/react": "^11.2.7",
    "@testing-library/user-event": "^12.8.3",
    "cra-append-sw": "^2.7.0",
    "react": "^17.0.2",
    "react-dom": "^17.0.2",
    "react-scripts": "4.0.3",
    "web-vitals": "^1.1.2"
  },

Backend Code

index.js

const express = require('express')
const dotenv = require('dotenv')
const bodyParser = require('body-parser')
const cors = require('cors')
const webpush = require('web-push')

const app = express()

dotenv.config()

app.use(cors())
app.use(bodyParser.json())
###You can generate VAPID keys using the command:
**./node_modules/.bin/web-push generate-vapid-keys**
webpush.setVapidDetails("mailto: `YOUR EMAIL OR WEBSITE ADDRESS`", "YOUR-PUBLIC-VAPID-KEY", "YOUR-PRIVATE-VAPID-KEY")

app.get('/', (req, res) => {
  res.send('Hello world!')
})

app.post('/notifications/subscribe', (req, res) => {
  console.log(req.body);
  const payload = JSON.stringify({
    title:req.body.title,
    description:req.body.description,
    icon:req.body.icon
  })
// console.log(req.body.subscription);
  webpush.sendNotification(req.body.subscription, payload)
    .then(result => console.log())
    .catch(e => console.log(e.stack))

  res.status(200).json({'success': true})
});

app.listen(8000, () => console.log('The server has been started on the port 8000'))

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