events: getMaxListeners detects 0 listeners

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>
nodejs · Feb 2, 2025 · bab9c4d · bab9c4d
1 parent 3af23a1
commit bab9c4d
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diff --git a/lib/events.js b/lib/events.js
@@ -939,7 +939,7 @@ 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);
+}