events: improve listeners() performance

PR-URL: #33863
Reviewed-By: Robert Nagy <ronagy@icloud.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>

Author: mscdex

benchmark/events/ee-listeners.js

@@ -14,7 +14,7 @@ function main({ n, listeners, raw }) {
 
   for (let k = 0; k < listeners; k += 1) {
     ee.on('dummy0', () => {});
-    ee.on('dummy1', () => {});
+    ee.once('dummy1', () => {});
   }
 
   if (raw === 'true') {

lib/events.js

@@ -22,7 +22,6 @@
 'use strict';
 
 const {
-  Array,
   Boolean,
   Error,
   MathMin,
@@ -613,9 +612,11 @@ function arrayClone(arr) {
 }
 
 function unwrapListeners(arr) {
-  const ret = new Array(arr.length);
+  const ret = arrayClone(arr);
   for (let i = 0; i < ret.length; ++i) {
-    ret[i] = arr[i].listener || arr[i];
+    const orig = ret[i].listener;
+    if (typeof orig === 'function')
+      ret[i] = orig;
   }
   return ret;
 }