fix: failsafe JavaScript event emitter notifyListeners (#3695)

* fix: failsafe JavaScript event emitter `notifyListeners` * chore: update change log
wailsapp · Aug 20, 2024 · 4b6a8e1 · 4b6a8e1
1 parent 868931f
commit 4b6a8e1
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Showing 3 changed files with 11 additions and 10 deletions.
diff --git a/v2/internal/frontend/runtime/desktop/events.js b/v2/internal/frontend/runtime/desktop/events.js
@@ -90,17 +90,17 @@ function notifyListeners(eventData) {
     // Get the event name
     let eventName = eventData.name;
 
-    // Check if we have any listeners for this event
-    if (eventListeners[eventName]) {
+    // Keep a list of listener indexes to destroy
+    const newEventListenerList = eventListeners[eventName]?.slice() || [];
 
-        // Keep a list of listener indexes to destroy
-        const newEventListenerList = eventListeners[eventName].slice();
+    // Check if we have any listeners for this event
+    if (newEventListenerList.length) {
 
         // Iterate listeners
-        for (let count = eventListeners[eventName].length - 1; count >= 0; count -= 1) {
+        for (let count = newEventListenerList.length - 1; count >= 0; count -= 1) {
 
             // Get next listener
-            const listener = eventListeners[eventName][count];
+            const listener = newEventListenerList[count];
 
             let data = eventData.data;
 

diff --git a/v2/internal/frontend/runtime/runtime_debug_desktop.js b/v2/internal/frontend/runtime/runtime_debug_desktop.js
diff --git a/website/src/pages/changelog.mdx b/website/src/pages/changelog.mdx
@@ -25,6 +25,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 + Modified `ZoomFactor` and `IsZoomControlEnabled` options to be Windows-only options in PR[#3644](https://github.com/wailsapp/wails/pull/3644) by @levinit
 - Added nil check for Drag-n-Drop on Windows. Fixed by in [PR](https://github.com/wailsapp/wails/pull/3597) by @leaanthony based on the suggestion by @Alpa-1 in [#3596](https://github.com/wailsapp/wails/issues/3596).
 - Fixed typos in various .mdx files. [PR #3628](https://github.com/wailsapp/wails/pull/3628) by [@deining](https://github.com/deining)
+- Fixed `notifyListeners()` race condition when terminated mid-emission [PR](https://github.com/wailsapp/wails/pull/3695) by [@mrf345](https://github.com/mrf345)
 
 ## v2.9.1 - 2024-06-18