From 81304dabd3b858efd2cc1ea94b5eaa224f0afa26 Mon Sep 17 00:00:00 2001
From: Robert Nagy <ronagy@icloud.com>
Date: Tue, 2 Sep 2025 21:05:21 +0200
Subject: [PATCH] http: lazy allocate cookies array

---
 lib/_http_outgoing.js | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/_http_outgoing.js b/lib/_http_outgoing.js
index fdd0f2f77eaac3..24aae1caca69d3 100644
--- a/lib/_http_outgoing.js
+++ b/lib/_http_outgoing.js
@@ -673,20 +673,22 @@ OutgoingMessage.prototype.setHeaders = function setHeaders(headers) {
   // We also cannot safely split by comma.
   // To avoid setHeader overwriting the previous value we push
   // set-cookie values in array and set them all at once.
-  const cookies = [];
+  let cookies = null;
 
   for (const { 0: key, 1: value } of headers) {
     if (key === 'set-cookie') {
       if (ArrayIsArray(value)) {
+        cookies ??= [];
         cookies.push(...value);
       } else {
+        cookies ??= [];
         cookies.push(value);
       }
       continue;
     }
     this.setHeader(key, value);
   }
-  if (cookies.length) {
+  if (cookies != null) {
     this.setHeader('set-cookie', cookies);
   }