fix-polyfill WebRTC-events-when-proto-is-non-writable-but-configurable

src/js/utils.js

@@ -31,13 +31,20 @@ export function wrapPeerConnectionEvent(window, eventNameToWrap, wrapper) {
   if (!window.RTCPeerConnection) {
     return;
   }
-  const addEventListener = Object.getOwnPropertyDescriptor(
-    EventTarget.prototype, 'addEventListener');
-  if (!addEventListener.writable) {
+
+  const proto = window.RTCPeerConnection.prototype;
+
+  const isAddEventListenerWritable =
+    tryMakePropertyWritable(proto, 'addEventListener');
+  const isRemoveEventListenerWritable =
+    tryMakePropertyWritable(proto, 'removeEventListener');
+  const canPolyfill =
+    isAddEventListenerWritable && isRemoveEventListenerWritable;
+
+  if (!canPolyfill) {
     log('Unable to polyfill events');
     return;
   }
-  const proto = window.RTCPeerConnection.prototype;
   const nativeAddEventListener = proto.addEventListener;
 
   proto.addEventListener = function(nativeEventName, cb) {
@@ -104,6 +111,28 @@ export function wrapPeerConnectionEvent(window, eventNameToWrap, wrapper) {
   });
 }
 
+/**
+ * Tries to ensure the property is writable.
+ * If the property is read-only but configurable,
+ * it will be redefined to be writable.
+ * @param {object} target the object to check the property on.
+ * @param {string} property the property to check.
+ * @return {boolean} true if the property is writable, false otherwise.
+ */
+export function tryMakePropertyWritable(target, property) {
+  try {
+    Object.defineProperty(target, property, {
+      value: target[property],
+      writable: true,
+      configurable: true,
+    });
+
+    return true;
+  } catch (e) {
+    return false;
+  }
+}
+
 export function disableLog(bool) {
   if (typeof bool !== 'boolean') {
     return new Error('Argument type: ' + typeof bool +

test/unit/wrapPeerConnectionEvent.test.js

@@ -0,0 +1,69 @@
+/*
+ *  Copyright (c) 2026 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree.
+ */
+
+describe('wrapPeerConnectionEvent', () => {
+  const wrapPeerConnectionEvent =
+		require('../../dist/utils.js').wrapPeerConnectionEvent;
+  let window;
+  let RTCPeerConnection;
+  let addEventListener;
+  let removeEventListener;
+
+  beforeEach(() => {
+    addEventListener = jest.fn();
+    removeEventListener = jest.fn();
+    RTCPeerConnection = jest.fn();
+
+    window = {
+      RTCPeerConnection,
+    };
+  });
+
+  it('should patch RTCPeerConnection if the props are writable', () => {
+    changeAccessorDescriptor({writable: false, configurable: true});
+
+    wrapPeerConnectionEvent(window, 'track', (e) => {
+      return {type: e.type, wrapped: true};
+    });
+
+    expect(RTCPeerConnection.prototype.addEventListener)
+      .not.toBe(addEventListener);
+    expect(RTCPeerConnection.prototype.removeEventListener)
+      .not.toBe(removeEventListener);
+  });
+
+  it('shouldn\'t patch RTCPeerConnection if the props are not configurable',
+    () => {
+      changeAccessorDescriptor({writable: false, configurable: false});
+
+      wrapPeerConnectionEvent(window, 'track', () => {
+        return null;
+      });
+
+      expect(RTCPeerConnection.prototype.addEventListener)
+        .toBe(addEventListener);
+      expect(RTCPeerConnection.prototype.removeEventListener)
+        .toBe(removeEventListener);
+    });
+
+  function changeAccessorDescriptor(
+    {writable, configurable},
+  ) {
+    Object.defineProperty(RTCPeerConnection.prototype, 'addEventListener', {
+      value: addEventListener,
+      writable,
+      configurable,
+    });
+    Object.defineProperty(RTCPeerConnection.prototype, 'removeEventListener', {
+      value: removeEventListener,
+      writable,
+      configurable,
+    });
+  }
+});
+