In this article i will explain you step by step how you can add email authentication with firebase in your nodejs application

Step 1: Create a Firebase Project or you can skip this step of you have already created your firebase project

• Go to https://firebase.google.com and click on Get Started

• Proceed to click on Create a project.

• Enter a project name and check yes if you wish to add analytics to your project.

• Wait for the project to be created.

Step 2: Create firebase credentials

• Once your project created go to ProjectOverview->Project Settings and scroll below and click on Add App

• Select Web option

Keep you credentials somewhere safe

Step 3: Enable email authentication from firebase

In order to enable email authentication from firebase

• Go to Authentication from left panel of firebase

• Go to sign-in method tab

• Click on Add new provider

• Select Email/Password and we are done

Step 4: Add firebase authentication code to firebase

• Install firebase

Go to your node project folder and install firebase

npm install firebase

• Copy paste the following code in your node js project and according to your node js project setup

import express from "express";
import path from "path";
import "dotenv/config";
import { initializeApp } from "firebase/app";
const app = express();
const port = 3000;
const __dirname = path.resolve();
const firebaseConfig = {
  apiKey: process.env.API_KEY,
  authDomain: process.env.AUTH_DOMAIN,
  databaseURL: process.env.DATABASE_URL,
  projectId: process.env.PROJECT_ID,
  storageBucket: process.env.STORAGE_BUCKET,
  messagingSenderId: process.env.MESSAGE_SENDER_ID,
  appId: process.env.APP_ID,
};
const firebase = initializeApp(firebaseConfig);

app.use(express.json());

app.use(express.static(path.join(__dirname, "src/public")));

app.get("/login", (req, res, next) => {
  res.sendFile(__dirname + "/src/public/index.html");
});

app.post("/signup", async (req, res, next) => {
  var email = req.body.email;
  var password = req.body.password;

  firebase
    .auth()
    .createUserWithEmailAndPassword(email, password)
    .then(function (userRecord) {
      console.log("User Created");
    })
    .catch(function (error) {
      console.log("Something went wrong");
    });
});

app.post("/authenticate", async (req, res, next) => {
  var email = req.body.email;
  var password = req.body.password;
  firebase
    .auth()
    .signInWithEmailAndPassword(email, password)
    .catch(function (error) {
      console.log(error.code);
      console.log(error.message);
    });
});

app.post("/logout", async (req, res, next) => {
  firebase
    .auth()
    .signOut()
    .then(
      function () {
        console.log("Logged out!");
      },
      function (error) {
        console.log(error.code);
        console.log(error.message);
      }
    );
});

app.listen(port, () => {
  console.log(`Demo app listening on port ${port}`);
});