refactor: avoid re subscribe for already subscribed entities (#486)

mohitpubnub · Mohit Tejani · pubnub-release-bot · web-flow · commit 9032b02e44e9 · 2025-12-04T16:07:34.000+05:30
* refactor: prevent event engine state transition when subsequent subscribe request contain existing channels or groups

* lib/dist updates

* refactor: remove filter for presence channels from subscriptionChanged status event in re-subscribe scenario

* PubNub SDK v10.2.4 release.

---------

Co-authored-by: Mohit Tejani &lt;mohit.tejani@Mohits-MacBook-Pro.local&gt;
Co-authored-by: PubNub Release Bot &lt;120067856+pubnub-release-bot@users.noreply.github.com&gt;
diff --git a/.pubnub.yml b/.pubnub.yml
@@ -1,5 +1,10 @@
 ---
 changelog:
+  - date: 2025-12-04
+    version: v10.2.4
+    changes:
+      - type: improvement
+        text: "Prevent resubscribe to previously subscribed entities."
   - date: 2025-11-20
     version: v10.2.3
     changes:
@@ -1369,7 +1374,7 @@ supported-platforms:
       - 'Ubuntu 14.04 and up'
       - 'Windows 7 and up'
     version: 'Pubnub Javascript for Node'
-version: '10.2.3'
+version: '10.2.4'
 sdks:
   - full-name: PubNub Javascript SDK
     short-name: Javascript
@@ -1385,7 +1390,7 @@ sdks:
           - distribution-type: source
             distribution-repository: GitHub release
             package-name: pubnub.js
-            location: https://github.com/pubnub/javascript/archive/refs/tags/v10.2.3.zip
+            location: https://github.com/pubnub/javascript/archive/refs/tags/v10.2.4.zip
             requires:
               - name: 'agentkeepalive'
                 min-version: '3.5.2'
@@ -2056,7 +2061,7 @@ sdks:
           - distribution-type: library
             distribution-repository: GitHub release
             package-name: pubnub.js
-            location: https://github.com/pubnub/javascript/releases/download/v10.2.3/pubnub.10.2.3.js
+            location: https://github.com/pubnub/javascript/releases/download/v10.2.4/pubnub.10.2.4.js
             requires:
               - name: 'agentkeepalive'
                 min-version: '3.5.2'
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,3 +1,9 @@
+## v10.2.4
+December 04 2025
+
+#### Modified
+- Prevent resubscribe to previously subscribed entities.
+
 ## v10.2.3
 November 20 2025
 
diff --git a/README.md b/README.md
@@ -27,8 +27,8 @@ Watch [Getting Started with PubNub JS SDK](https://app.dashcam.io/replay/64ee0d2
      npm install pubnub
      ```
    * or download one of our builds from our CDN: 
-     * https://cdn.pubnub.com/sdk/javascript/pubnub.10.2.3.js
-     * https://cdn.pubnub.com/sdk/javascript/pubnub.10.2.3.min.js
+     * https://cdn.pubnub.com/sdk/javascript/pubnub.10.2.4.js
+     * https://cdn.pubnub.com/sdk/javascript/pubnub.10.2.4.min.js
 
 2. Configure your keys:
 
diff --git a/dist/web/pubnub.js b/dist/web/pubnub.js
@@ -5436,7 +5436,7 @@
 	            return base.PubNubFile;
 	        },
 	        get version() {
-	            return '10.2.3';
+	            return '10.2.4';
 	        },
 	        getVersion() {
 	            return this.version;
@@ -9566,6 +9566,11 @@
 	        return subscriptionTimetokenFromReference(currentTimetoken, referenceTimetoken !== null && referenceTimetoken !== void 0 ? referenceTimetoken : '0');
 	    }
 	    subscribe({ channels, channelGroups, timetoken, withPresence, }) {
+	        var _a;
+	        // check if the channels and groups are already subscribed
+	        const hasNewChannels = channels === null || channels === void 0 ? void 0 : channels.some((channel) => !this.channels.includes(channel));
+	        const hasNewGroups = channelGroups === null || channelGroups === void 0 ? void 0 : channelGroups.some((group) => !this.groups.includes(group));
+	        const hasNewSubscriptions = hasNewChannels || hasNewGroups;
 	        this.channels = [...this.channels, ...(channels !== null && channels !== void 0 ? channels : [])];
 	        this.groups = [...this.groups, ...(channelGroups !== null && channelGroups !== void 0 ? channelGroups : [])];
 	        if (withPresence) {
@@ -9576,7 +9581,29 @@
 	            this.engine.transition(restore(Array.from(new Set([...this.channels, ...(channels !== null && channels !== void 0 ? channels : [])])), Array.from(new Set([...this.groups, ...(channelGroups !== null && channelGroups !== void 0 ? channelGroups : [])])), timetoken));
 	        }
 	        else {
-	            this.engine.transition(subscriptionChange(Array.from(new Set([...this.channels, ...(channels !== null && channels !== void 0 ? channels : [])])), Array.from(new Set([...this.groups, ...(channelGroups !== null && channelGroups !== void 0 ? channelGroups : [])]))));
+	            if (hasNewSubscriptions) {
+	                this.engine.transition(subscriptionChange(Array.from(new Set([...this.channels, ...(channels !== null && channels !== void 0 ? channels : [])])), Array.from(new Set([...this.groups, ...(channelGroups !== null && channelGroups !== void 0 ? channelGroups : [])]))));
+	            }
+	            else {
+	                this.dependencies.config
+	                    .logger()
+	                    .debug('EventEngine', 'Skipping state transition - all channels/groups already subscribed. Emitting SubscriptionChanged event.');
+	                // Get current timetoken from state context
+	                const currentState = this.engine.currentState;
+	                const currentContext = this.engine.currentContext;
+	                let currentTimetoken = '0';
+	                if ((currentState === null || currentState === void 0 ? void 0 : currentState.label) === ReceivingState.label && currentContext) {
+	                    const receivingContext = currentContext;
+	                    currentTimetoken = (_a = receivingContext.cursor) === null || _a === void 0 ? void 0 : _a.timetoken;
+	                }
+	                // Manually emit SubscriptionChanged status event
+	                this.dependencies.emitStatus({
+	                    category: StatusCategory$1.PNSubscriptionChangedCategory,
+	                    affectedChannels: Array.from(new Set(this.channels)),
+	                    affectedChannelGroups: Array.from(new Set(this.groups)),
+	                    currentTimetoken,
+	                });
+	            }
 	        }
 	        if (this.dependencies.join) {
 	            this.dependencies.join({
diff --git a/dist/web/pubnub.min.js b/dist/web/pubnub.min.js
diff --git a/lib/core/components/configuration.js b/lib/core/components/configuration.js
@@ -168,7 +168,7 @@ const makeConfiguration = (base, setupCryptoModule) => {
             return base.PubNubFile;
         },
         get version() {
-            return '10.2.3';
+            return '10.2.4';
         },
         getVersion() {
             return this.version;
diff --git a/lib/event-engine/index.js b/lib/event-engine/index.js
@@ -37,13 +37,17 @@ var __importStar = (this && this.__importStar) || (function () {
         return result;
     };
 })();
+var __importDefault = (this && this.__importDefault) || function (mod) {
+    return (mod && mod.__esModule) ? mod : { "default": mod };
+};
 Object.defineProperty(exports, "__esModule", { value: true });
 exports.EventEngine = void 0;
 const receiving_1 = require("./states/receiving");
 const dispatcher_1 = require("./dispatcher");
 const utils_1 = require("../core/utils");
 const unsubscribed_1 = require("./states/unsubscribed");
 const core_1 = require("./core");
+const categories_1 = __importDefault(require("../core/constants/categories"));
 const utils = __importStar(require("../core/utils"));
 const events = __importStar(require("./events"));
 /**
@@ -88,6 +92,11 @@ class EventEngine {
         return (0, utils_1.subscriptionTimetokenFromReference)(currentTimetoken, referenceTimetoken !== null && referenceTimetoken !== void 0 ? referenceTimetoken : '0');
     }
     subscribe({ channels, channelGroups, timetoken, withPresence, }) {
+        var _a;
+        // check if the channels and groups are already subscribed
+        const hasNewChannels = channels === null || channels === void 0 ? void 0 : channels.some((channel) => !this.channels.includes(channel));
+        const hasNewGroups = channelGroups === null || channelGroups === void 0 ? void 0 : channelGroups.some((group) => !this.groups.includes(group));
+        const hasNewSubscriptions = hasNewChannels || hasNewGroups;
         this.channels = [...this.channels, ...(channels !== null && channels !== void 0 ? channels : [])];
         this.groups = [...this.groups, ...(channelGroups !== null && channelGroups !== void 0 ? channelGroups : [])];
         if (withPresence) {
@@ -98,7 +107,29 @@ class EventEngine {
             this.engine.transition(events.restore(Array.from(new Set([...this.channels, ...(channels !== null && channels !== void 0 ? channels : [])])), Array.from(new Set([...this.groups, ...(channelGroups !== null && channelGroups !== void 0 ? channelGroups : [])])), timetoken));
         }
         else {
-            this.engine.transition(events.subscriptionChange(Array.from(new Set([...this.channels, ...(channels !== null && channels !== void 0 ? channels : [])])), Array.from(new Set([...this.groups, ...(channelGroups !== null && channelGroups !== void 0 ? channelGroups : [])]))));
+            if (hasNewSubscriptions) {
+                this.engine.transition(events.subscriptionChange(Array.from(new Set([...this.channels, ...(channels !== null && channels !== void 0 ? channels : [])])), Array.from(new Set([...this.groups, ...(channelGroups !== null && channelGroups !== void 0 ? channelGroups : [])]))));
+            }
+            else {
+                this.dependencies.config
+                    .logger()
+                    .debug('EventEngine', 'Skipping state transition - all channels/groups already subscribed. Emitting SubscriptionChanged event.');
+                // Get current timetoken from state context
+                const currentState = this.engine.currentState;
+                const currentContext = this.engine.currentContext;
+                let currentTimetoken = '0';
+                if ((currentState === null || currentState === void 0 ? void 0 : currentState.label) === receiving_1.ReceivingState.label && currentContext) {
+                    const receivingContext = currentContext;
+                    currentTimetoken = (_a = receivingContext.cursor) === null || _a === void 0 ? void 0 : _a.timetoken;
+                }
+                // Manually emit SubscriptionChanged status event
+                this.dependencies.emitStatus({
+                    category: categories_1.default.PNSubscriptionChangedCategory,
+                    affectedChannels: Array.from(new Set(this.channels)),
+                    affectedChannelGroups: Array.from(new Set(this.groups)),
+                    currentTimetoken,
+                });
+            }
         }
         if (this.dependencies.join) {
             this.dependencies.join({
diff --git a/package-lock.json b/package-lock.json
diff --git a/package.json b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "pubnub",
-  "version": "10.2.3",
+  "version": "10.2.4",
   "author": "PubNub <support@pubnub.com>",
   "description": "Publish & Subscribe Real-time Messaging with PubNub",
   "scripts": {
diff --git a/src/core/components/configuration.ts b/src/core/components/configuration.ts
@@ -236,7 +236,7 @@ export const makeConfiguration = (
       return base.PubNubFile;
     },
     get version(): string {
-      return '10.2.3';
+      return '10.2.4';
     },
     getVersion(): string {
       return this.version;
diff --git a/src/event-engine/index.ts b/src/event-engine/index.ts
@@ -9,6 +9,7 @@ import { Dependencies, EventEngineDispatcher } from './dispatcher';
 import { subscriptionTimetokenFromReference } from '../core/utils';
 import { UnsubscribedState } from './states/unsubscribed';
 import { Dispatcher, Engine } from './core';
+import categoryConstants from '../core/constants/categories';
 import * as utils from '../core/utils';
 import * as effects from './effects';
 import * as events from './events';
@@ -79,6 +80,11 @@ export class EventEngine {
     timetoken?: string | number;
     withPresence?: boolean;
   }): void {
+    // check if the channels and groups are already subscribed
+    const hasNewChannels = channels?.some((channel) => !this.channels.includes(channel));
+    const hasNewGroups = channelGroups?.some((group) => !this.groups.includes(group));
+    const hasNewSubscriptions = hasNewChannels || hasNewGroups;
+
     this.channels = [...this.channels, ...(channels ?? [])];
     this.groups = [...this.groups, ...(channelGroups ?? [])];
 
@@ -95,12 +101,38 @@ export class EventEngine {
         ),
       );
     } else {
-      this.engine.transition(
-        events.subscriptionChange(
-          Array.from(new Set([...this.channels, ...(channels ?? [])])),
-          Array.from(new Set([...this.groups, ...(channelGroups ?? [])])),
-        ),
-      );
+      if (hasNewSubscriptions) {
+        this.engine.transition(
+          events.subscriptionChange(
+            Array.from(new Set([...this.channels, ...(channels ?? [])])),
+            Array.from(new Set([...this.groups, ...(channelGroups ?? [])])),
+          ),
+        );
+      } else {
+        this.dependencies.config
+          .logger()
+          .debug(
+            'EventEngine',
+            'Skipping state transition - all channels/groups already subscribed. Emitting SubscriptionChanged event.',
+          );
+        // Get current timetoken from state context
+        const currentState = this.engine.currentState;
+        const currentContext = this.engine.currentContext;
+        let currentTimetoken: string | undefined = '0';
+
+        if (currentState?.label === ReceivingState.label && currentContext) {
+          const receivingContext = currentContext as ReceivingStateContext;
+          currentTimetoken = receivingContext.cursor?.timetoken;
+        }
+
+        // Manually emit SubscriptionChanged status event
+        this.dependencies.emitStatus({
+          category: categoryConstants.PNSubscriptionChangedCategory,
+          affectedChannels: Array.from(new Set(this.channels)),
+          affectedChannelGroups: Array.from(new Set(this.groups)),
+          currentTimetoken,
+        });
+      }
     }
     if (this.dependencies.join) {
       this.dependencies.join({
diff --git a/test/unit/event_engine.test.ts b/test/unit/event_engine.test.ts

Original file line number	Diff line number	Diff line change
`@@ -1,6 +1,6 @@`
`1`	`1`	`{`
`2`	`2`	`"name": "pubnub",`
`3`		`- "version": "10.2.3",`
	`3`	`+ "version": "10.2.4",`
`4`	`4`	`"author": "PubNub <support@pubnub.com>",`
`5`	`5`	`"description": "Publish & Subscribe Real-time Messaging with PubNub",`
`6`	`6`	`"scripts": {`