rtdb_sample_presence_app.js

// This snippet file was generated by processing the source file:
// ./database-next/offline.js
//
// To make edits to the snippets in this file, please edit the source

// [START rtdb_sample_presence_app_modular]
import { getDatabase, ServerValue } from "firebase/database";

// Since I can connect from multiple devices or browser tabs, we store each connection instance separately
// any time that connectionsRef's value is null (i.e. has no children) I am offline
const db = getDatabase(firebaseApp);
const myConnectionsRef = db.ref('users/joe/connections');

// stores the timestamp of my last disconnect (the last time I was seen online)
const lastOnlineRef = db.ref('users/joe/lastOnline');

const connectedRef = db.ref('.info/connected');
connectedRef.on('value', (snap) => {
  if (snap.val() === true) {
    // We're connected (or reconnected)! Do anything here that should happen only if online (or on reconnect)
    const con = myConnectionsRef.push();

    // When I disconnect, remove this device
    con.onDisconnect().remove();

    // Add this device to my connections list
    // this value could contain info about the device or a timestamp too
    con.set(true);

    // When I disconnect, update the last time I was seen online
    lastOnlineRef.onDisconnect().set(ServerValue.TIMESTAMP);
  }
});
// [END rtdb_sample_presence_app_modular]