[FSSDK-10201] queueMicrotask alternative for unsupported platforms (#933)

* [FSSDK-10201] queueMicrotask alternative for unsupported platforms

* [FSSDK-10201] dir rename, testcase addition

* [FSSDK-10201] test improvement, redundant code removal

* [FSSDK-10201] licence text addition, only removal

* [FSSDK-10201] unused import removal

Author: junaed-optimizely

lib/core/odp/odp_event_manager.ts

@@ -24,6 +24,7 @@ import { OdpConfig } from './odp_config';
 import { IOdpEventApiManager } from './odp_event_api_manager';
 import { invalidOdpDataFound } from './odp_utils';
 import { IUserAgentParser } from './user_agent_parser';
+import { scheduleMicrotaskOrTimeout } from '../../utils/microtask';
 
 const MAX_RETRIES = 3;
 
@@ -393,14 +394,14 @@ export abstract class OdpEventManager implements IOdpEventManager {
 
     if (batch.length > 0) {
       // put sending the event on another event loop
-      queueMicrotask(async () => {
+      scheduleMicrotaskOrTimeout(async () => {
         let shouldRetry: boolean;
         let attemptNumber = 0;
         do {
           shouldRetry = await this.apiManager.sendEvents(odpConfig, batch);
           attemptNumber += 1;
         } while (shouldRetry && attemptNumber < this.retries);
-      });
+      })
     }
   }
 

lib/core/project_config/project_config_manager.ts

@@ -20,6 +20,7 @@ import { ERROR_MESSAGES } from '../../utils/enums';
 import { createOptimizelyConfig } from '../optimizely_config';
 import { OnReadyResult, OptimizelyConfig, DatafileManager } from '../../shared_types';
 import { ProjectConfig, toDatafile, tryCreatingProjectConfig } from '../project_config';
+import { scheduleMicrotaskOrTimeout } from '../../utils/microtask';
 
 const logger = getLogger();
 const MODULE_NAME = 'PROJECT_CONFIG_MANAGER';
@@ -189,10 +190,9 @@ export class ProjectConfigManager {
       if (configObj && oldRevision !== configObj.revision) {
         this.configObj = configObj;
         this.optimizelyConfigObj = null;
-        
-        queueMicrotask(() => {
+        scheduleMicrotaskOrTimeout(() => {
           this.updateListeners.forEach(listener => listener(configObj));
-        });
+        }) 
       }
     }
 

lib/utils/microtask/index.tests.js

@@ -0,0 +1,38 @@
+/**
+ * Copyright 2024, Optimizely
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { scheduleMicrotaskOrTimeout } from './'; 
+
+describe('scheduleMicrotaskOrTimeout', () => {
+  it('should use queueMicrotask if available', (done) => {
+    // Assuming queueMicrotask is available in the environment
+    scheduleMicrotaskOrTimeout(() => {
+      done();
+    });
+  });
+
+  it('should fallback to setTimeout if queueMicrotask is not available', (done) => {
+    // Temporarily remove queueMicrotask to test the fallback
+    const originalQueueMicrotask = window.queueMicrotask;
+    window.queueMicrotask = undefined;
+
+    scheduleMicrotaskOrTimeout(() => {
+      // Restore queueMicrotask before calling done
+      window.queueMicrotask = originalQueueMicrotask;
+      done();
+    });
+  });
+});

lib/utils/microtask/index.ts

@@ -0,0 +1,25 @@
+/**
+ * Copyright 2024, Optimizely
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+type Callback = () => void; 
+
+export const scheduleMicrotaskOrTimeout = (callback: Callback): void =>{
+  if (typeof queueMicrotask === 'function') {
+    queueMicrotask(callback);
+  } else {
+    setTimeout(callback);
+  }
+}