feat: Remove event target shim.

packages/sdk/react-native/package.json

@@ -45,8 +45,7 @@
   "dependencies": {
     "@launchdarkly/js-client-sdk-common": "1.3.0",
     "@react-native-async-storage/async-storage": "^1.21.0",
-    "base64-js": "^1.5.1",
-    "event-target-shim": "^6.0.2"
+    "base64-js": "^1.5.1"
   },
   "devDependencies": {
     "@launchdarkly/private-js-mocks": "0.0.1",

packages/sdk/react-native/src/index.ts

@@ -5,12 +5,9 @@
  *
  * @packageDocumentation
  */
-import { setupPolyfill } from './polyfills';
 import ReactNativeLDClient from './ReactNativeLDClient';
 import RNOptions from './RNOptions';
 
-setupPolyfill();
-
 export * from '@launchdarkly/js-client-sdk-common';
 
 export * from './hooks';

packages/sdk/react-native/src/polyfills/index.ts

@@ -1,13 +1,4 @@
-import EventTarget from 'event-target-shim';
-
 import { type Hasher, sha256 } from '../fromExternal/js-sha256';
 import { base64FromByteArray, btoa } from './btoa';
-import CustomEvent from './CustomEvent';
 
-function setupPolyfill() {
-  Object.assign(global, {
-    EventTarget,
-    CustomEvent,
-  });
-}
-export { base64FromByteArray, btoa, type Hasher, setupPolyfill, sha256 };
+export { base64FromByteArray, btoa, type Hasher, sha256 };

packages/shared/sdk-client/src/api/LDEmitter.test.ts

@@ -1,14 +1,21 @@
-import { LDContext } from '@launchdarkly/js-sdk-common';
+import { LDContext, LDLogger } from '@launchdarkly/js-sdk-common';
 
 import LDEmitter from './LDEmitter';
 
 describe('LDEmitter', () => {
   const error = { type: 'network', message: 'unreachable' };
   let emitter: LDEmitter;
+  let logger: LDLogger;
 
   beforeEach(() => {
     jest.resetAllMocks();
-    emitter = new LDEmitter();
+    logger = {
+      debug: jest.fn(),
+      info: jest.fn(),
+      warn: jest.fn(),
+      error: jest.fn(),
+    };
+    emitter = new LDEmitter(logger);
   });
 
   test('subscribe and handle', () => {
@@ -77,12 +84,13 @@ describe('LDEmitter', () => {
 
   test('on listener with arguments', () => {
     const context = { kind: 'user', key: 'test-user-1' };
-    const onListener = jest.fn((c: LDContext) => c);
+    const arg2 = { test: 'test' };
+    const onListener = jest.fn((c: LDContext, a2: any) => [c, a2]);
 
     emitter.on('change', onListener);
-    emitter.emit('change', context);
+    emitter.emit('change', context, arg2);
 
-    expect(onListener).toBeCalledWith(context);
+    expect(onListener).toBeCalledWith(context, arg2);
   });
 
   test('unsubscribe one of many listeners', () => {
@@ -131,4 +139,15 @@ describe('LDEmitter', () => {
     expect(errorHandler1).not.toBeCalled();
     expect(errorHandler2).not.toBeCalled();
   });
+
+  it('handles errors generated by the callback', () => {
+    emitter.on('error', () => {
+      throw new Error('toast');
+    });
+    // Should not have an uncaught exception.
+    emitter.emit('error');
+    expect(logger.error).toHaveBeenCalledWith(
+      'Encountered error invoking handler for "error", detail: "Error: toast"',
+    );
+  });
 });

packages/shared/sdk-client/src/api/LDEmitter.ts

@@ -1,53 +1,20 @@
+import { LDLogger } from '@launchdarkly/js-sdk-common';
+
 export type EventName = 'error' | 'change';
 
-type CustomEventListeners = {
-  original: Function;
-  custom: Function;
-};
-/**
- * Native api usage: EventTarget.
- *
- * This is an event emitter using the standard built-in EventTarget web api.
- * https://developer.mozilla.org/en-US/docs/Web/API/EventTarget
- *
- * In react-native use event-target-shim to polyfill EventTarget. This is safe
- * because the react-native repo uses it too.
- * https://github.com/mysticatea/event-target-shim
- */
 export default class LDEmitter {
-  private et: EventTarget = new EventTarget();
+  private listeners: Map<EventName, Function[]> = new Map();
 
-  private listeners: Map<EventName, CustomEventListeners[]> = new Map();
+  constructor(private logger?: LDLogger) {}
 
-  /**
-   * Cache all listeners in a Map so we can remove them later
-   * @param name string event name
-   * @param originalListener pointer to the original function as specified by
-   * the consumer
-   * @param customListener pointer to the custom function based on original
-   * listener. This is needed to allow for CustomEvents.
-   * @private
-   */
-  private saveListener(name: EventName, originalListener: Function, customListener: Function) {
-    const listener = { original: originalListener, custom: customListener };
+  on(name: EventName, listener: Function) {
     if (!this.listeners.has(name)) {
       this.listeners.set(name, [listener]);
     } else {
       this.listeners.get(name)?.push(listener);
     }
   }
 
-  on(name: EventName, listener: Function) {
-    const customListener = (e: Event) => {
-      const { detail } = e as CustomEvent;
-
-      // invoke listener with args from CustomEvent
-      listener(...detail);
-    };
-    this.saveListener(name, listener, customListener);
-    this.et.addEventListener(name, customListener);
-  }
-
   /**
    * Unsubscribe one or all events.
    *
@@ -61,11 +28,8 @@ export default class LDEmitter {
     }
 
     if (listener) {
-      const toBeRemoved = existingListeners.find((c) => c.original === listener);
-      this.et.removeEventListener(name, toBeRemoved?.custom as any);
-
       // remove from internal cache
-      const updated = existingListeners.filter((l) => l.original !== listener);
+      const updated = existingListeners.filter((fn) => fn !== listener);
       if (updated.length === 0) {
         this.listeners.delete(name);
       } else {
@@ -74,15 +38,21 @@ export default class LDEmitter {
       return;
     }
 
-    // remove all listeners
-    existingListeners.forEach((l) => {
-      this.et.removeEventListener(name, l.custom as any);
-    });
+    // listener was not specified, so remove them all for that event
     this.listeners.delete(name);
   }
 
+  private invokeListener(listener: Function, name: EventName, ...detail: any[]) {
+    try {
+      listener(...detail);
+    } catch (err) {
+      this.logger?.error(`Encountered error invoking handler for "${name}", detail: "${err}"`);
+    }
+  }
+
   emit(name: EventName, ...detail: any[]) {
-    this.et.dispatchEvent(new CustomEvent(name, { detail }));
+    const listeners = this.listeners.get(name);
+    listeners?.forEach((listener) => this.invokeListener(listener, name, ...detail));
   }
 
   eventNames(): string[] {