I use firebase for authentication on JS. Everything is making in client side. Anyone can look my js files, copy the config datas, can make own project. How can I hide that datas? Because my plan is "pay as you go", If anyone copy that data, i have a big trouble. What should I do?

Maybe Firebase REST API can solve my problem. Is there any example about authentication with REST API.

I tried move codes Node.js but I couldnt handle it. You can see my index.js, It is on functions folder. I deploy it to firebase hosting. Authentication doesnt work.

const functions = require("firebase-functions");
const admin = require("firebase-admin");
const express = require("express");
const config = require('./config.js');
const app = express();
admin.initializeApp(config);

const app2 = initializeApp(config);

const auth = getAuth();
// // Create and Deploy Your First Cloud Functions
// // https://firebase.google.com/docs/functions/write-firebase-functions
//
app.post("/",  async (req, res) => {
  const user = req.body;

  await admin.firestore().collection("users").add(user);
  const mail=user.Email;
  const pass=user.Password;


  createUserWithEmailAndPassword(auth, mail, pass)
.then((userCredential) => {
  // Signed in 
  const user = userCredential.user;
  // ...
})
.catch((error) => {
  const errorCode = error.code;
  const errorMessage = error.message;
  // ..
});
  
  
 });
 exports.widgets = functions.https.onRequest(app);