Firebase Has a Free API That Goes Way Beyond Authentication

#firebase #javascript #webdev #google

Firebase is Google's app platform, and most devs only scratch the surface with Auth and Firestore. Its JavaScript SDK exposes powerful APIs for real-time data, storage, ML, and more.

Firestore Real-Time Listeners

import { collection, query, where, onSnapshot, orderBy, limit } from "firebase/firestore";

const q = query(
  collection(db, "scrapedProducts"),
  where("price", "<", 50),
  orderBy("scrapedAt", "desc"),
  limit(100)
);

const unsubscribe = onSnapshot(q, (snapshot) => {
  snapshot.docChanges().forEach((change) => {
    if (change.type === "added") console.log("New product:", change.doc.data());
    if (change.type === "modified") console.log("Price changed:", change.doc.data());
    if (change.type === "removed") console.log("Removed:", change.doc.id);
  });
});

Real-time sync across all connected clients — zero WebSocket setup.

Firestore Aggregation Queries

import { getAggregateFromServer, collection, query, where, sum, average, count } from "firebase/firestore";

const snapshot = await getAggregateFromServer(
  query(collection(db, "products"), where("category", "==", "electronics")),
  {
    totalPrice: sum("price"),
    avgPrice: average("price"),
    count: count()
  }
);

console.log("Total:", snapshot.data().totalPrice);
console.log("Average:", snapshot.data().avgPrice);
console.log("Count:", snapshot.data().count);

Cloud Functions Callable API

// Client side
import { getFunctions, httpsCallable } from "firebase/functions";

const functions = getFunctions();
const scrapeUrl = httpsCallable(functions, "scrapeUrl");

const result = await scrapeUrl({ url: "https://example.com", selectors: ["h1", ".price"] });
console.log(result.data); // { title: "...", price: "$29.99" }

Firebase Storage: Resumable Uploads

import { ref, uploadBytesResumable, getDownloadURL } from "firebase/storage";

const storageRef = ref(storage, `exports/${userId}/${filename}`);
const uploadTask = uploadBytesResumable(storageRef, file);

uploadTask.on("state_changed",
  (snapshot) => {
    const progress = (snapshot.bytesTransferred / snapshot.totalBytes) * 100;
    console.log(`Upload: ${progress}%`);
  },
  (error) => console.error(error),
  async () => {
    const url = await getDownloadURL(uploadTask.snapshot.ref);
    console.log("Download URL:", url);
  }
);

Firebase Auth: Beyond Email/Password

import { signInWithPopup, GoogleAuthProvider, linkWithCredential, EmailAuthProvider } from "firebase/auth";

// Sign in with Google
const result = await signInWithPopup(auth, new GoogleAuthProvider());

// Link additional email/password to same account
const credential = EmailAuthProvider.credential(email, password);
await linkWithCredential(result.user, credential);

// Custom claims (admin-only)
const token = await result.user.getIdTokenResult();
if (token.claims.admin) showAdminPanel();

Remote Config: A/B Testing API

import { fetchAndActivate, getValue } from "firebase/remote-config";

await fetchAndActivate(remoteConfig);
const showNewFeature = getValue(remoteConfig, "show_new_scraper_ui").asBoolean();
const maxResults = getValue(remoteConfig, "max_scrape_results").asNumber();