From 774302b9bbf527e0e954813fb25bc285fa398bc2 Mon Sep 17 00:00:00 2001
From: Aaron O'Mullan <aaron.omullan@gmail.com>
Date: Fri, 1 Oct 2021 12:17:16 +0200
Subject: [PATCH] perf(fetch): optimize fillHeaders() key iteration (#12287)

Reduces self-time by ~70x (~70ms => ~1ms on 1M iters)

for...in filtered by hasOwnProperty yields the same set of keys as Object.keys()
---
 ext/fetch/20_headers.js | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/ext/fetch/20_headers.js b/ext/fetch/20_headers.js
index c35c745b58..04ff104a2d 100644
--- a/ext/fetch/20_headers.js
+++ b/ext/fetch/20_headers.js
@@ -29,7 +29,7 @@
     ArrayPrototypeJoin,
     ArrayPrototypeSplice,
     ArrayPrototypeFilter,
-    ObjectKeys,
+    ObjectPrototypeHasOwnProperty,
     ObjectEntries,
     RegExpPrototypeTest,
     Symbol,
@@ -76,7 +76,10 @@
         appendHeader(headers, header[0], header[1]);
       }
     } else {
-      for (const key of ObjectKeys(object)) {
+      for (const key in object) {
+        if (!ObjectPrototypeHasOwnProperty(object, key)) {
+          continue;
+        }
         appendHeader(headers, key, object[key]);
       }
     }