lib: switch to Number.isNaN

Number.isNaN is now as fast as `val !== val`. Switch to the more
readable version. Also switch all `isNaN` to `Number.isNaN`.

PR-URL: https://github.com/nodejs/node/pull/18744
Reviewed-By: Weijia Wang <starkwang@126.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

1 files changed, 2 insertions, 4 deletions

diff --git a/lib/events.js b/lib/events.js
index 9ad5ec376f..aec30e7239 100644
--- a/lib/events.js
+++ b/lib/events.js
@@ -52,9 +52,7 @@ Object.defineProperty(EventEmitter, 'defaultMaxListeners', {
     return defaultMaxListeners;
   },
   set: function(arg) {
-    // check whether the input is a positive number (whose value is zero or
-    // greater and not a NaN).
-    if (typeof arg !== 'number' || arg < 0 || arg !== arg) {
+    if (typeof arg !== 'number' || arg < 0 || Number.isNaN(arg)) {
       const errors = lazyErrors();
       throw new errors.RangeError('ERR_OUT_OF_RANGE',
                                   'defaultMaxListeners',
@@ -79,7 +77,7 @@ EventEmitter.init = function() {
 // Obviously not all Emitters should be limited to 10. This function allows
 // that to be increased. Set to zero for unlimited.
 EventEmitter.prototype.setMaxListeners = function setMaxListeners(n) {
-  if (typeof n !== 'number' || n < 0 || isNaN(n)) {
+  if (typeof n !== 'number' || n < 0 || Number.isNaN(n)) {
     const errors = lazyErrors();
     throw new errors.RangeError('ERR_OUT_OF_RANGE', 'n',
                                 'a non-negative number', n);