From 4d4c20d5400725955c2b0b09a6d858e7b9739172 Mon Sep 17 00:00:00 2001
From: Sebastian Schmidt <mrschmidt@google.com>
Date: Mon, 27 Apr 2020 09:20:39 -0700
Subject: [PATCH] Check for addEventListener() before calling

---
 packages/firestore/src/util/async_queue.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/firestore/src/util/async_queue.ts b/packages/firestore/src/util/async_queue.ts
index 7b4bde18262..8fbbc4f5208 100644
--- a/packages/firestore/src/util/async_queue.ts
+++ b/packages/firestore/src/util/async_queue.ts
@@ -240,7 +240,7 @@ export class AsyncQueue {
 
   constructor() {
     const window = PlatformSupport.getPlatform().window;
-    if (window) {
+    if (window && typeof window.addEventListener === 'function') {
       window.addEventListener('visibilitychange', this.visibilityHandler);
     }
   }