Firebase in a chrome extension

Adding firebase/firestore to chrome extension

based on stackoverflow Add Cloud firestore library to chrome extension, content_scripts

in chrome extension manifest file manifest.json add firebase-app.js (https://www.gstatic.com/firebasejs/7.5.0/firebase-app.js) and firebase-firestore.js(https://www.gstatic.com/firebasejs/7.5.0/firebase-firestore.js) as follows

...
  "content_scripts": [
    {
      "matches": [
        "https://www.wsj.com/*"
      ],
      "js": [
        "firebasejs/7.5.0/firebase-app.js",
        "firebasejs/7.5.0/firebase-firestore.js",
    ...

As well as

  ...
  "content_security_policy":"script-src 'self' https://www.gstatic.com/ https://*.firebaseio.com https://www.googleapis.com; object-src 'self'"
}

then in your extension code you can just initialise firebase as usual eg

const firebaseConfig = {
    apiKey: "XXX",
    authDomain: "XXX",
    databaseURL: "XXX",
    projectId: "XXX",
    storageBucket: "XXX",
    messagingSenderId: "XXX",
    appId: "XXX",
    measurementId: "XXX"
  };

firebase.initializeApp(firebaseConfig);
const db = firebase.firestore();

// do something with firebase/firestore