index.js

const { initializeApp } = require('firebase/app');
const {getAuth,signInWithEmailAndPassword} = require("firebase/auth");
const prompt = require('prompt');
require('dotenv').config();

// Initialize Firebase App.
initializeApp({
  apiKey: process.env.FIREBASE_API_KEY,
  authDomain: process.env.FIREBASE_AUTH_DOMAIN,
  projectId: process.env.FIREBASE_PROJECT_ID,
});

// Start and setup prompt.
prompt.start();
prompt.get(
  {
    properties: {
      email: {
        required: true,
      },
      password: {
        required: true,
        hidden: true,
      },
    },
  },
  function(err, result) {
    let email = result.email;
    let password = result.password;

    // Authenticate user using email and password.
    var auth = getAuth();
      signInWithEmailAndPassword(auth,email, password)
        .then(async function(response) {
          let idtoken = await auth.currentUser.getIdToken();
          console.log(idtoken);
        // Get the access token of the authenticated user.
        // firebase
        //   .auth()
        //   .currentUser.getIdToken()
        //   .then(token => {
        //     console.log(token);
        //   });
      })
      .catch(error => {
        console.error(error);
      });
  },
);