From 18ac7d40c87b380ce5ed617bd7c59e344730a883 Mon Sep 17 00:00:00 2001
From: Yoshiya Hinosawa <stibium121@gmail.com>
Date: Thu, 21 Jan 2021 16:44:48 +0900
Subject: fix(runtime): fix recursive dispatches of unload event (#9207)

---
 runtime/js/30_os.js   | 9 ++++++---
 runtime/js/99_main.js | 9 +++++++++
 2 files changed, 15 insertions(+), 3 deletions(-)

(limited to 'runtime/js')

diff --git a/runtime/js/30_os.js b/runtime/js/30_os.js
index 1d700b561..5a3c990b0 100644
--- a/runtime/js/30_os.js
+++ b/runtime/js/30_os.js
@@ -24,9 +24,12 @@
   }
 
   function exit(code = 0) {
-    // Invokes the `unload` hooks before exiting
-    // ref: https://github.com/denoland/deno/issues/3603
-    window.dispatchEvent(new Event("unload"));
+    // Dispatches `unload` only when it's not dispatched yet.
+    if (!window[Symbol.for("isUnloadDispatched")]) {
+      // Invokes the `unload` hooks before exiting
+      // ref: https://github.com/denoland/deno/issues/3603
+      window.dispatchEvent(new Event("unload"));
+    }
     core.jsonOpSync("op_exit", { code });
     throw new Error("Code not reachable");
   }
diff --git a/runtime/js/99_main.js b/runtime/js/99_main.js
index a6abc8d27..fd846af20 100644
--- a/runtime/js/99_main.js
+++ b/runtime/js/99_main.js
@@ -305,6 +305,15 @@ delete Object.prototype.__proto__;
     defineEventHandler(window, "load", null);
     defineEventHandler(window, "unload", null);
 
+    const isUnloadDispatched = Symbol.for("isUnloadDispatched");
+    // Stores the flag for checking whether unload is dispatched or not.
+    // This prevents the recursive dispatches of unload events.
+    // See https://github.com/denoland/deno/issues/9201.
+    window[isUnloadDispatched] = false;
+    window.addEventListener("unload", () => {
+      window[isUnloadDispatched] = true;
+    });
+
     runtimeStart(runtimeOptions);
     const {
       args,
-- 
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