fix: check if BroadcastChannel is open before sending (#17366)

Fixes #16978

2 files changed, 12 insertions, 2 deletions

diff --git a/cli/tests/unit/broadcast_channel_test.ts b/cli/tests/unit/broadcast_channel_test.ts
index 06821c4db..b13a47574 100644
--- a/cli/tests/unit/broadcast_channel_test.ts
+++ b/cli/tests/unit/broadcast_channel_test.ts
@@ -2,7 +2,7 @@
 import { assertEquals } from "../../../test_util/std/testing/asserts.ts";
 import { deferred } from "../../../test_util/std/async/deferred.ts";
 
-Deno.test("broadcastchannel worker", async () => {
+Deno.test("BroadcastChannel worker", async () => {
   const intercom = new BroadcastChannel("intercom");
   let count = 0;
 
@@ -27,3 +27,9 @@ Deno.test("broadcastchannel worker", async () => {
 
   await promise;
 });
+
+Deno.test("BroadcastChannel immediate close after post", () => {
+  const bc = new BroadcastChannel("internal_notification");
+  bc.postMessage("New listening connected!");
+  bc.close();
+});
diff --git a/ext/broadcast_channel/01_broadcast_channel.js b/ext/broadcast_channel/01_broadcast_channel.js
index cf3b17ac5..59c6b7cef 100644
--- a/ext/broadcast_channel/01_broadcast_channel.js
+++ b/ext/broadcast_channel/01_broadcast_channel.js
@@ -122,7 +122,11 @@
       dispatch(this, this[_name], new Uint8Array(data));
 
       // Send to listeners in other VMs.
-      defer(() => core.opAsync("op_broadcast_send", rid, this[_name], data));
+      defer(() => {
+        if (!this[_closed]) {
+          core.opAsync("op_broadcast_send", rid, this[_name], data);
+        }
+      });
     }
 
     close() {