Add RTDB offline snippets

database-next/offline.js

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+// [SNIPPET_REGISTRY disabled]
+// [SNIPPETS_SEPARATION enabled]
+
+import { initializeApp } from "firebase/app";
+
+const firebaseApp = initializeApp({
+  apiKey: '### FIREBASE API KEY ###',
+  appId: '### FIREBASE APP ID ###',
+  projectId: '### FIREBASE PROJECT ID ###'
+});
+
+function onDisconnectSimple() {
+  // [START rtdb_ondisconnect_simple]
+  const { getDatabase } = require("firebase/database");
+
+  const db = getDatabase(firebaseApp);
+  const presenceRef = db.ref("disconnectmessage");
+  // Write a string when this client loses connection
+  presenceRef.onDisconnect().set("I disconnected!");
+  // [END rtdb_ondisconnect_simple]
+}
+
+function onDisconnectCallback() {
+  const { getDatabase } = require("firebase/database");
+
+  const db = getDatabase(firebaseApp);
+  const presenceRef = db.ref("disconnectmessage");
+
+  // [START rtdb_ondisconnect_callback]
+  presenceRef.onDisconnect().remove((err) => {
+    if (err) {
+      console.error("could not establish onDisconnect event", err);
+    }
+  });
+  // [END rtdb_ondisconnect_callback]
+}
+
+function onDisconnectCancel() {
+  const { getDatabase } = require("firebase/database");
+
+  const db = getDatabase(firebaseApp);
+  const presenceRef = db.ref("disconnectmessage");
+
+  // [START rtdb_ondisconnect_cancel]
+  const onDisconnectRef = presenceRef.onDisconnect();
+  onDisconnectRef.set("I disconnected");
+  // some time later when we change our minds
+  onDisconnectRef.cancel();
+  // [END rtdb_ondisconnect_cancel]
+}
+
+function detectConnectionState() {
+  // [START rtdb_detect_connection_state]
+  const { getDatabase } = require("firebase/database");
+
+  const db = getDatabase(firebaseApp);
+  const connectedRef = db.ref(".info/connected");
+  connectedRef.on("value", (snap) => {
+    if (snap.val() === true) {
+      console.log("connected");
+    } else {
+      console.log("not connected");
+    }
+  });
+  // [END rtdb_detect_connection_state]
+}
+
+function setServerTimestamp() {
+  // [START rtdb_set_server_timestamp]
+  const { getDatabase, ServerValue } = require("firebase/database");
+
+  const db = getDatabase(firebaseApp);
+  const userLastOnlineRef = db.ref("users/joe/lastOnline");
+  userLastOnlineRef.onDisconnect().set(ServerValue.TIMESTAMP);
+  // [END rtdb_set_server_timestamp]
+}
+
+function estimateClockSkew() {
+  // [START rtdb_estimate_clock_skew]
+  const { getDatabase } = require("firebase/database");
+
+  const db = getDatabase(firebaseApp);
+  const offsetRef = db.ref(".info/serverTimeOffset");
+  offsetRef.on("value", (snap) => {
+    const offset = snap.val();
+    const estimatedServerTimeMs = new Date().getTime() + offset;
+  });
+  // [END rtdb_estimate_clock_skew]
+}
+
+function samplePresenceApp() {
+  // [START rtdb_sample_presence_app]
+  const { getDatabase, ServerValue } = require("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]
+}

database/offline.js

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+// These samples are intended for Web so this import would normally be
+// done in HTML however using modules here is more convenient for
+// ensuring sample correctness offline.
+import firebase from "firebase/app";
+import "firebase/database";
+
+function onDisconnectSimple() {
+  // [START rtdb_ondisconnect_simple]
+  var presenceRef = firebase.database().ref("disconnectmessage");
+  // Write a string when this client loses connection
+  presenceRef.onDisconnect().set("I disconnected!");
+  // [END rtdb_ondisconnect_simple]
+}
+
+function onDisconnectCallback() {
+  var presenceRef = firebase.database().ref("disconnectmessage");
+
+  // [START rtdb_ondisconnect_callback]
+  presenceRef.onDisconnect().remove((err) => {
+    if (err) {
+      console.error("could not establish onDisconnect event", err);
+    }
+  });
+  // [END rtdb_ondisconnect_callback]
+}
+
+function onDisconnectCancel() {
+  var presenceRef = firebase.database().ref("disconnectmessage");
+
+  // [START rtdb_ondisconnect_cancel]
+  var onDisconnectRef = presenceRef.onDisconnect();
+  onDisconnectRef.set("I disconnected");
+  // some time later when we change our minds
+  onDisconnectRef.cancel();
+  // [END rtdb_ondisconnect_cancel]
+}
+
+function detectConnectionState() {
+  // [START rtdb_detect_connection_state]
+  var connectedRef = firebase.database().ref(".info/connected");
+  connectedRef.on("value", (snap) => {
+    if (snap.val() === true) {
+      console.log("connected");
+    } else {
+      console.log("not connected");
+    }
+  });
+  // [END rtdb_detect_connection_state]
+}
+
+function setServerTimestamp() {
+  // [START rtdb_set_server_timestamp]
+  var userLastOnlineRef = firebase.database().ref("users/joe/lastOnline");
+  userLastOnlineRef.onDisconnect().set(firebase.database.ServerValue.TIMESTAMP);
+  // [END rtdb_set_server_timestamp]
+}
+
+function estimateClockSkew() {
+  // [START rtdb_estimate_clock_skew]
+  var offsetRef = firebase.database().ref(".info/serverTimeOffset");
+  offsetRef.on("value", (snap) => {
+    var offset = snap.val();
+    var estimatedServerTimeMs = new Date().getTime() + offset;
+  });
+  // [END rtdb_estimate_clock_skew]
+}
+
+function samplePresenceApp() {
+  // [START rtdb_sample_presence_app]
+  // 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
+  var myConnectionsRef = firebase.database().ref('users/joe/connections');
+
+  // stores the timestamp of my last disconnect (the last time I was seen online)
+  var lastOnlineRef = firebase.database().ref('users/joe/lastOnline');
+
+  var connectedRef = firebase.database().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)
+      var 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(firebase.database.ServerValue.TIMESTAMP);
+    }
+  });
+  // [END rtdb_sample_presence_app]
+}

snippets/database-next/offline/rtdb_detect_connection_state.js

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+// 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_detect_connection_state_modular]
+import { getDatabase } from "firebase/database";
+
+const db = getDatabase(firebaseApp);
+const connectedRef = db.ref(".info/connected");
+connectedRef.on("value", (snap) => {
+  if (snap.val() === true) {
+    console.log("connected");
+  } else {
+    console.log("not connected");
+  }
+});
+// [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:
+// ./database-next/offline.js
+//
+// To make edits to the snippets in this file, please edit the source
+
+// [START rtdb_estimate_clock_skew_modular]
+import { getDatabase } from "firebase/database";
+
+const db = getDatabase(firebaseApp);
+const offsetRef = db.ref(".info/serverTimeOffset");
+offsetRef.on("value", (snap) => {
+  const offset = snap.val();
+  const estimatedServerTimeMs = new Date().getTime() + offset;
+});
+// [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:
+// ./database-next/offline.js
+//
+// To make edits to the snippets in this file, please edit the source
+
+// [START rtdb_ondisconnect_callback_modular]
+presenceRef.onDisconnect().remove((err) => {
+  if (err) {
+    console.error("could not establish onDisconnect event", err);
+  }
+});
+// [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:
+// ./database-next/offline.js
+//
+// To make edits to the snippets in this file, please edit the source
+
+// [START rtdb_ondisconnect_cancel_modular]
+const onDisconnectRef = presenceRef.onDisconnect();
+onDisconnectRef.set("I disconnected");
+// some time later when we change our minds
+onDisconnectRef.cancel();
+// [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:
+// ./database-next/offline.js
+//
+// To make edits to the snippets in this file, please edit the source
+
+// [START rtdb_ondisconnect_simple_modular]
+import { getDatabase } from "firebase/database";
+
+const db = getDatabase(firebaseApp);
+const presenceRef = db.ref("disconnectmessage");
+// Write a string when this client loses connection
+presenceRef.onDisconnect().set("I disconnected!");
+// [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:
+// ./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]

snippets/database-next/offline/rtdb_set_server_timestamp.js

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+// 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_set_server_timestamp_modular]
+import { getDatabase, ServerValue } from "firebase/database";
+
+const db = getDatabase(firebaseApp);
+const userLastOnlineRef = db.ref("users/joe/lastOnline");
+userLastOnlineRef.onDisconnect().set(ServerValue.TIMESTAMP);
+// [END rtdb_set_server_timestamp_modular]