Answer by zarpio for How to implement Firebase Cloud Messaging (FCM) with Nuxt.js

Step 1) Install dependencies

npm install firebasenpm install @nuxtjs/firebase

Step 2) Create a file serviceWorker.js on your project's root folder.

self.addEventListener('push', function (e) {data = e.data.json();  var options = {    body: data.notification.body,    icon: data.notification.icon,    vibrate: [100, 50, 100],    data: {    dateOfArrival: Date.now(),    primaryKey: '2'  },};

Step 3) Config your nuxt.config.js as follows.

Add this line to the top of your file.

const fs = require('fs')

Update your modules array with firebase credentials.

['@nuxtjs/firebase',  {    config: {      apiKey: "<yourKey>",      authDomain: "<yourAuthDomain>",      projectId: "<yourProjectId>",      storageBucket: "<yourStorageBucket>",      messagingSenderId: "<yourMessagingSenderId>",      appId: "<yourAppId>",      measurementId: ",<yourMeasurementId>"    },    onFirebaseHosting: false,    services: {      messaging: {        createServiceWorker: true,        fcmPublicVapidKey: '<yourFCMPublicVapidKey>',        inject: fs.readFileSync('./serviceWorker.js')      }    }  }]

Step 4 > Finally.. to your index.js or layout file.

async mounted() {  const currentToken = await this.$fire.messaging.getToken()  const data = JSON.stringify({    notification: {      title: 'firebase',      body: 'firebase is awesome',      click_action: 'http://localhost:3000/',      icon: 'http://localhost:3000/assets/images/brand-logo.png'    },     to: currentToken  })  const config = {    method: 'post',    url: 'https://fcm.googleapis.com/fcm/send',    headers: { 'Content-Type': 'application/json', 'Authorization': 'key=<yourServerKey>'    },    data  };  const response = await axios(config)  this.$fire.messaging.onMessage((payload) => {    console.info('Message received: ', payload)  })  this.$fire.messaging.onTokenRefresh(async () => {    const refreshToken = await this.$fire.messaging.getToken()    console.log('Token Refreshed',refreshToken)  })}

For more details, to understand the steps, you can visit this article.