events: getMaxListeners detects 0 listeners

KhafraDev · aduh95 · commit 64180421c2c0 · 2025-04-02T15:15:48.000+02:00
PR-URL: #56807 Refs: nodejs/undici#4032 Refs: c1ccade Reviewed-By: Robert Nagy <ronagy@icloud.com> Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com> Reviewed-By: Luigi Pinca <luigipinca@gmail.com> Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com> Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: Chemi Atlow <chemi@atlow.co.il>
diff --git a/lib/events.js b/lib/events.js
@@ -950,7 +950,7 @@ function getEventListeners(emitterOrTarget, type) {
 function getMaxListeners(emitterOrTarget) {
   if (typeof emitterOrTarget?.getMaxListeners === 'function') {
     return _getMaxListeners(emitterOrTarget);
-  } else if (emitterOrTarget?.[kMaxEventTargetListeners]) {
+  } else if (typeof emitterOrTarget?.[kMaxEventTargetListeners] === 'number') {
     return emitterOrTarget[kMaxEventTargetListeners];
   }
 
diff --git a/test/parallel/test-events-getmaxlisteners.js b/test/parallel/test-events-getmaxlisteners.js
@@ -17,3 +17,8 @@ const { getMaxListeners, EventEmitter, defaultMaxListeners, setMaxListeners } =
   setMaxListeners(101, et);
   assert.strictEqual(getMaxListeners(et), 101);
 }
+
+{
+  const ac = new AbortController();
+  assert.strictEqual(getMaxListeners(ac.signal), 0);
+}

Original file line number	Diff line number	Diff line change
`@@ -950,7 +950,7 @@ function getEventListeners(emitterOrTarget, type) {`
`950`	`950`	`function getMaxListeners(emitterOrTarget) {`
`951`	`951`	`if (typeof emitterOrTarget?.getMaxListeners === 'function') {`
`952`	`952`	`return _getMaxListeners(emitterOrTarget);`
`953`		`- } else if (emitterOrTarget?.[kMaxEventTargetListeners]) {`
	`953`	`+ } else if (typeof emitterOrTarget?.[kMaxEventTargetListeners] === 'number') {`
`954`	`954`	`return emitterOrTarget[kMaxEventTargetListeners];`
`955`	`955`	`}`
`956`	`956`
Original file line number	Diff line number	Diff line change
`@@ -17,3 +17,8 @@ const { getMaxListeners, EventEmitter, defaultMaxListeners, setMaxListeners } =`
`17`	`17`	`setMaxListeners(101, et);`
`18`	`18`	`assert.strictEqual(getMaxListeners(et), 101);`
`19`	`19`	`}`
	`20`	`+`
	`21`	`+{`
	`22`	`+ const ac = new AbortController();`
	`23`	`+ assert.strictEqual(getMaxListeners(ac.signal), 0);`
	`24`	`+}`