From 02ca358155297dc68fcc4c2ac312c26e10524e47 Mon Sep 17 00:00:00 2001
From: Mikhail Bodrov <bodrovmiha@yandex.ru>
Date: Mon, 27 Dec 2021 22:09:36 +0200
Subject: [PATCH] [Robustness] `stringify`: avoid relying on a global
 `undefined` (#427)

---
 lib/stringify.js | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lib/stringify.js b/lib/stringify.js
index f70820f9..bdc19c65 100644
--- a/lib/stringify.js
+++ b/lib/stringify.js
@@ -118,7 +118,7 @@ var stringify = function stringify(
     var objKeys;
     if (generateArrayPrefix === 'comma' && isArray(obj)) {
         // we need to join elements in
-        objKeys = [{ value: obj.length > 0 ? obj.join(',') || null : undefined }];
+        objKeys = [{ value: obj.length > 0 ? obj.join(',') || null : void undefined }];
     } else if (isArray(filter)) {
         objKeys = filter;
     } else {
@@ -128,7 +128,7 @@ var stringify = function stringify(
 
     for (var j = 0; j < objKeys.length; ++j) {
         var key = objKeys[j];
-        var value = typeof key === 'object' && key.value !== undefined ? key.value : obj[key];
+        var value = typeof key === 'object' && typeof key.value !== 'undefined' ? key.value : obj[key];
 
         if (skipNulls && value === null) {
             continue;
@@ -164,7 +164,7 @@ var normalizeStringifyOptions = function normalizeStringifyOptions(opts) {
         return defaults;
     }
 
-    if (opts.encoder !== null && opts.encoder !== undefined && typeof opts.encoder !== 'function') {
+    if (opts.encoder !== null && typeof opts.encoder !== 'undefined' && typeof opts.encoder !== 'function') {
         throw new TypeError('Encoder has to be a function.');
     }