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samtsternsamtstern
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Add RTDB offline snippets (#98)
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‎database-next/offline.js

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// [SNIPPET_REGISTRY disabled]
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// [SNIPPETS_SEPARATION enabled]
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import { initializeApp } from "firebase/app";
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const firebaseApp = initializeApp({
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apiKey: '### FIREBASE API KEY ###',
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appId: '### FIREBASE APP ID ###',
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projectId: '### FIREBASE PROJECT ID ###'
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});
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function onDisconnectSimple() {
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// [START rtdb_ondisconnect_simple]
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const { getDatabase } = require("firebase/database");
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const db = getDatabase(firebaseApp);
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const presenceRef = db.ref("disconnectmessage");
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// Write a string when this client loses connection
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presenceRef.onDisconnect().set("I disconnected!");
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// [END rtdb_ondisconnect_simple]
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}
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function onDisconnectCallback() {
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const { getDatabase } = require("firebase/database");
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const db = getDatabase(firebaseApp);
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const presenceRef = db.ref("disconnectmessage");
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// [START rtdb_ondisconnect_callback]
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presenceRef.onDisconnect().remove((err) => {
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if (err) {
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console.error("could not establish onDisconnect event", err);
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}
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});
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// [END rtdb_ondisconnect_callback]
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}
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function onDisconnectCancel() {
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const { getDatabase } = require("firebase/database");
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const db = getDatabase(firebaseApp);
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const presenceRef = db.ref("disconnectmessage");
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// [START rtdb_ondisconnect_cancel]
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const onDisconnectRef = presenceRef.onDisconnect();
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onDisconnectRef.set("I disconnected");
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// some time later when we change our minds
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onDisconnectRef.cancel();
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// [END rtdb_ondisconnect_cancel]
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}
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function detectConnectionState() {
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// [START rtdb_detect_connection_state]
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const { getDatabase } = require("firebase/database");
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const db = getDatabase(firebaseApp);
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const connectedRef = db.ref(".info/connected");
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connectedRef.on("value", (snap) => {
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if (snap.val() === true) {
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console.log("connected");
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} else {
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console.log("not connected");
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}
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});
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// [END rtdb_detect_connection_state]
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}
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function setServerTimestamp() {
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// [START rtdb_set_server_timestamp]
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const { getDatabase, ServerValue } = require("firebase/database");
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const db = getDatabase(firebaseApp);
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const userLastOnlineRef = db.ref("users/joe/lastOnline");
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userLastOnlineRef.onDisconnect().set(ServerValue.TIMESTAMP);
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// [END rtdb_set_server_timestamp]
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}
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function estimateClockSkew() {
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// [START rtdb_estimate_clock_skew]
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const { getDatabase } = require("firebase/database");
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const db = getDatabase(firebaseApp);
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const offsetRef = db.ref(".info/serverTimeOffset");
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offsetRef.on("value", (snap) => {
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const offset = snap.val();
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const estimatedServerTimeMs = new Date().getTime() + offset;
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});
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// [END rtdb_estimate_clock_skew]
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}
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function samplePresenceApp() {
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// [START rtdb_sample_presence_app]
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const { getDatabase, ServerValue } = require("firebase/database");
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// Since I can connect from multiple devices or browser tabs, we store each connection instance separately
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// any time that connectionsRef's value is null (i.e. has no children) I am offline
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const db = getDatabase(firebaseApp);
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const myConnectionsRef = db.ref('users/joe/connections');
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// stores the timestamp of my last disconnect (the last time I was seen online)
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const lastOnlineRef = db.ref('users/joe/lastOnline');
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const connectedRef = db.ref('.info/connected');
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connectedRef.on('value', (snap) => {
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if (snap.val() === true) {
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// We're connected (or reconnected)! Do anything here that should happen only if online (or on reconnect)
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const con = myConnectionsRef.push();
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// When I disconnect, remove this device
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con.onDisconnect().remove();
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// Add this device to my connections list
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// this value could contain info about the device or a timestamp too
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con.set(true);
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// When I disconnect, update the last time I was seen online
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lastOnlineRef.onDisconnect().set(ServerValue.TIMESTAMP);
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}
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});
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// [END rtdb_sample_presence_app]
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}

‎database/offline.js

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// These samples are intended for Web so this import would normally be
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// done in HTML however using modules here is more convenient for
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// ensuring sample correctness offline.
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import firebase from "firebase/app";
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import "firebase/database";
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function onDisconnectSimple() {
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// [START rtdb_ondisconnect_simple]
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var presenceRef = firebase.database().ref("disconnectmessage");
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// Write a string when this client loses connection
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presenceRef.onDisconnect().set("I disconnected!");
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// [END rtdb_ondisconnect_simple]
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}
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function onDisconnectCallback() {
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var presenceRef = firebase.database().ref("disconnectmessage");
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// [START rtdb_ondisconnect_callback]
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presenceRef.onDisconnect().remove((err) => {
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if (err) {
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console.error("could not establish onDisconnect event", err);
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}
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});
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// [END rtdb_ondisconnect_callback]
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}
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function onDisconnectCancel() {
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var presenceRef = firebase.database().ref("disconnectmessage");
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// [START rtdb_ondisconnect_cancel]
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var onDisconnectRef = presenceRef.onDisconnect();
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onDisconnectRef.set("I disconnected");
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// some time later when we change our minds
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onDisconnectRef.cancel();
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// [END rtdb_ondisconnect_cancel]
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}
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function detectConnectionState() {
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// [START rtdb_detect_connection_state]
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var connectedRef = firebase.database().ref(".info/connected");
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connectedRef.on("value", (snap) => {
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if (snap.val() === true) {
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console.log("connected");
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} else {
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console.log("not connected");
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}
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});
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// [END rtdb_detect_connection_state]
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}
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function setServerTimestamp() {
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// [START rtdb_set_server_timestamp]
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var userLastOnlineRef = firebase.database().ref("users/joe/lastOnline");
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userLastOnlineRef.onDisconnect().set(firebase.database.ServerValue.TIMESTAMP);
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// [END rtdb_set_server_timestamp]
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}
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function estimateClockSkew() {
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// [START rtdb_estimate_clock_skew]
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var offsetRef = firebase.database().ref(".info/serverTimeOffset");
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offsetRef.on("value", (snap) => {
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var offset = snap.val();
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var estimatedServerTimeMs = new Date().getTime() + offset;
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});
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// [END rtdb_estimate_clock_skew]
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}
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function samplePresenceApp() {
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// [START rtdb_sample_presence_app]
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// Since I can connect from multiple devices or browser tabs, we store each connection instance separately
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// any time that connectionsRef's value is null (i.e. has no children) I am offline
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var myConnectionsRef = firebase.database().ref('users/joe/connections');
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// stores the timestamp of my last disconnect (the last time I was seen online)
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var lastOnlineRef = firebase.database().ref('users/joe/lastOnline');
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var connectedRef = firebase.database().ref('.info/connected');
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connectedRef.on('value', (snap) => {
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if (snap.val() === true) {
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// We're connected (or reconnected)! Do anything here that should happen only if online (or on reconnect)
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var con = myConnectionsRef.push();
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// When I disconnect, remove this device
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con.onDisconnect().remove();
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// Add this device to my connections list
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// this value could contain info about the device or a timestamp too
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con.set(true);
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// When I disconnect, update the last time I was seen online
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lastOnlineRef.onDisconnect().set(firebase.database.ServerValue.TIMESTAMP);
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}
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});
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// [END rtdb_sample_presence_app]
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}

‎snippets/database-next/offline/rtdb_detect_connection_state.js

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// This snippet file was generated by processing the source file:
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// ./database-next/offline.js
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//
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// To make edits to the snippets in this file, please edit the source
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// [START rtdb_detect_connection_state_modular]
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import { getDatabase } from "firebase/database";
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const db = getDatabase(firebaseApp);
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const connectedRef = db.ref(".info/connected");
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connectedRef.on("value", (snap) => {
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if (snap.val() === true) {
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console.log("connected");
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} else {
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console.log("not connected");
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}
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});
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// [END rtdb_detect_connection_state_modular]

‎snippets/database-next/offline/rtdb_estimate_clock_skew.js

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// This snippet file was generated by processing the source file:
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// ./database-next/offline.js
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//
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// To make edits to the snippets in this file, please edit the source
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// [START rtdb_estimate_clock_skew_modular]
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import { getDatabase } from "firebase/database";
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const db = getDatabase(firebaseApp);
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const offsetRef = db.ref(".info/serverTimeOffset");
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offsetRef.on("value", (snap) => {
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const offset = snap.val();
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const estimatedServerTimeMs = new Date().getTime() + offset;
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});
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// [END rtdb_estimate_clock_skew_modular]

‎snippets/database-next/offline/rtdb_ondisconnect_callback.js

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// This snippet file was generated by processing the source file:
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// ./database-next/offline.js
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//
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// To make edits to the snippets in this file, please edit the source
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// [START rtdb_ondisconnect_callback_modular]
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presenceRef.onDisconnect().remove((err) => {
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if (err) {
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console.error("could not establish onDisconnect event", err);
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}
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});
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// [END rtdb_ondisconnect_callback_modular]

‎snippets/database-next/offline/rtdb_ondisconnect_cancel.js

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// This snippet file was generated by processing the source file:
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// ./database-next/offline.js
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//
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// To make edits to the snippets in this file, please edit the source
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// [START rtdb_ondisconnect_cancel_modular]
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const onDisconnectRef = presenceRef.onDisconnect();
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onDisconnectRef.set("I disconnected");
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// some time later when we change our minds
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onDisconnectRef.cancel();
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// [END rtdb_ondisconnect_cancel_modular]

‎snippets/database-next/offline/rtdb_ondisconnect_simple.js

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// This snippet file was generated by processing the source file:
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// ./database-next/offline.js
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//
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// To make edits to the snippets in this file, please edit the source
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// [START rtdb_ondisconnect_simple_modular]
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import { getDatabase } from "firebase/database";
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const db = getDatabase(firebaseApp);
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const presenceRef = db.ref("disconnectmessage");
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// Write a string when this client loses connection
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presenceRef.onDisconnect().set("I disconnected!");
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// [END rtdb_ondisconnect_simple_modular]

‎snippets/database-next/offline/rtdb_sample_presence_app.js

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// This snippet file was generated by processing the source file:
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// ./database-next/offline.js
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//
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// To make edits to the snippets in this file, please edit the source
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// [START rtdb_sample_presence_app_modular]
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import { getDatabase, ServerValue } from "firebase/database";
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// Since I can connect from multiple devices or browser tabs, we store each connection instance separately
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// any time that connectionsRef's value is null (i.e. has no children) I am offline
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const db = getDatabase(firebaseApp);
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const myConnectionsRef = db.ref('users/joe/connections');
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// stores the timestamp of my last disconnect (the last time I was seen online)
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const lastOnlineRef = db.ref('users/joe/lastOnline');
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const connectedRef = db.ref('.info/connected');
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connectedRef.on('value', (snap) => {
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if (snap.val() === true) {
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// We're connected (or reconnected)! Do anything here that should happen only if online (or on reconnect)
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const con = myConnectionsRef.push();
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// When I disconnect, remove this device
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con.onDisconnect().remove();
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// Add this device to my connections list
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// this value could contain info about the device or a timestamp too
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con.set(true);
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// When I disconnect, update the last time I was seen online
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lastOnlineRef.onDisconnect().set(ServerValue.TIMESTAMP);
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}
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});
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// [END rtdb_sample_presence_app_modular]

‎snippets/database-next/offline/rtdb_set_server_timestamp.js

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// This snippet file was generated by processing the source file:
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// ./database-next/offline.js
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//
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// To make edits to the snippets in this file, please edit the source
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// [START rtdb_set_server_timestamp_modular]
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import { getDatabase, ServerValue } from "firebase/database";
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const db = getDatabase(firebaseApp);
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const userLastOnlineRef = db.ref("users/joe/lastOnline");
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userLastOnlineRef.onDisconnect().set(ServerValue.TIMESTAMP);
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// [END rtdb_set_server_timestamp_modular]

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