From 2e705fe8e47ea437ea99176571f73ab5bbdb8a16 Mon Sep 17 00:00:00 2001
From: Trivikram Kamat <16024985+trivikr@users.noreply.github.com>
Date: Sat, 14 Dec 2019 08:32:41 -0500
Subject: [PATCH 01/10] http: for of in lib/_http_agent.js

---
 lib/_http_agent.js | 21 +++++++--------------
 1 file changed, 7 insertions(+), 14 deletions(-)

diff --git a/lib/_http_agent.js b/lib/_http_agent.js
index 69fdb819a3a330..e47cbb2106fc8f 100644
--- a/lib/_http_agent.js
+++ b/lib/_http_agent.js
@@ -146,9 +146,8 @@ function maybeEnableKeylog(eventName) {
       agent.emit('keylog', keylog, this);
     };
     // Existing sockets will start listening on keylog now.
-    const sockets = ObjectValues(this.sockets);
-    for (let i = 0; i < sockets.length; i++) {
-      sockets[i].on('keylog', this[kOnKeylog]);
+    for (socket of ObjectValues(this.sockets)) {
+      socket.on('keylog', this[kOnKeylog]);
     }
   }
 }
@@ -346,9 +345,7 @@ Agent.prototype.removeSocket = function removeSocket(s, options) {
   if (!s.writable)
     sets.push(this.freeSockets);
 
-  for (let sk = 0; sk < sets.length; sk++) {
-    const sockets = sets[sk];
-
+  for (sockets of sets) {
     if (sockets[name]) {
       const index = sockets[name].indexOf(s);
       if (index !== -1) {
@@ -383,14 +380,10 @@ Agent.prototype.reuseSocket = function reuseSocket(socket, req) {
 };
 
 Agent.prototype.destroy = function destroy() {
-  const sets = [this.freeSockets, this.sockets];
-  for (let s = 0; s < sets.length; s++) {
-    const set = sets[s];
-    const keys = ObjectKeys(set);
-    for (let v = 0; v < keys.length; v++) {
-      const setName = set[keys[v]];
-      for (let n = 0; n < setName.length; n++) {
-        setName[n].destroy();
+  for (set of [this.freeSockets, this.sockets]) {
+    for (key of ObjectKeys(set)) {
+      for (setName of set[key]) {
+        setName.destroy();
       }
     }
   }

From 63f73b9a8ffe7ef8f03058460751ffcf329bb5b3 Mon Sep 17 00:00:00 2001
From: Trivikram Kamat <16024985+trivikr@users.noreply.github.com>
Date: Sat, 14 Dec 2019 08:39:27 -0500
Subject: [PATCH 02/10] http: for of in lib/_http_client.js

---
 lib/_http_client.js | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/lib/_http_client.js b/lib/_http_client.js
index 7888ce27d570ac..7f668b022ff774 100644
--- a/lib/_http_client.js
+++ b/lib/_http_client.js
@@ -230,9 +230,7 @@ function ClientRequest(input, options, cb) {
   const headersArray = ArrayIsArray(options.headers);
   if (!headersArray) {
     if (options.headers) {
-      const keys = ObjectKeys(options.headers);
-      for (let i = 0; i < keys.length; i++) {
-        const key = keys[i];
+      for (key of ObjectKeys(options.headers)) {
         this.setHeader(key, options.headers[key]);
       }
     }

From 3ba1da23078b7ffd3a73a164e807095e42a3e837 Mon Sep 17 00:00:00 2001
From: Trivikram Kamat <16024985+trivikr@users.noreply.github.com>
Date: Sat, 14 Dec 2019 08:44:54 -0500
Subject: [PATCH 03/10] http: for of in lib/_http_server.js

---
 lib/_http_server.js | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/lib/_http_server.js b/lib/_http_server.js
index 453cf9005363dc..173c43b370a2c8 100644
--- a/lib/_http_server.js
+++ b/lib/_http_server.js
@@ -262,9 +262,8 @@ function writeHead(statusCode, reason, obj) {
     // Slow-case: when progressive API and header fields are passed.
     let k;
     if (obj) {
-      const keys = ObjectKeys(obj);
-      for (let i = 0; i < keys.length; i++) {
-        k = keys[i];
+      for (key of ObjectKeys(obj)) {
+        k = key;
         if (k) this.setHeader(k, obj[k]);
       }
     }

From b4b4d3da28e841eb986ff39840b0b763f3bd5569 Mon Sep 17 00:00:00 2001
From: Trivikram Kamat <16024985+trivikr@users.noreply.github.com>
Date: Sat, 14 Dec 2019 08:51:55 -0500
Subject: [PATCH 04/10] http: for of in lib/_http_outgoing.js

---
 lib/_http_outgoing.js | 39 +++++++++++++--------------------------
 1 file changed, 13 insertions(+), 26 deletions(-)

diff --git a/lib/_http_outgoing.js b/lib/_http_outgoing.js
index f40cf923f9b377..066edc58626eec 100644
--- a/lib/_http_outgoing.js
+++ b/lib/_http_outgoing.js
@@ -165,9 +165,7 @@ ObjectDefineProperty(OutgoingMessage.prototype, '_headers', {
       this[kOutHeaders] = null;
     } else if (typeof val === 'object') {
       const headers = this[kOutHeaders] = ObjectCreate(null);
-      const keys = ObjectKeys(val);
-      for (var i = 0; i < keys.length; ++i) {
-        const name = keys[i];
+      for (name of ObjectKeys(val)) {
         headers[name.toLowerCase()] = [name, val[name]];
       }
     }
@@ -188,9 +186,7 @@ ObjectDefineProperty(OutgoingMessage.prototype, '_headerNames', {
     const headers = this[kOutHeaders];
     if (headers !== null) {
       const out = ObjectCreate(null);
-      const keys = ObjectKeys(headers);
-      for (var i = 0; i < keys.length; ++i) {
-        const key = keys[i];
+      for (key of ObjectKeys(headers)) {
         const val = headers[key][0];
         out[key] = val;
       }
@@ -203,11 +199,10 @@ ObjectDefineProperty(OutgoingMessage.prototype, '_headerNames', {
       const headers = this[kOutHeaders];
       if (!headers)
         return;
-      const keys = ObjectKeys(val);
-      for (var i = 0; i < keys.length; ++i) {
-        const header = headers[keys[i]];
+      for (key of ObjectKeys(val)) {
+        const header = headers[key];
         if (header)
-          header[0] = val[keys[i]];
+          header[0] = val[key];
       }
     }
   }, 'OutgoingMessage.prototype._headerNames is deprecated', 'DEP0066')
@@ -223,9 +218,7 @@ OutgoingMessage.prototype._renderHeaders = function _renderHeaders() {
   const headers = {};
 
   if (headersMap !== null) {
-    const keys = ObjectKeys(headersMap);
-    for (var i = 0, l = keys.length; i < l; i++) {
-      const key = keys[i];
+    for (key of ObjectKeys(headersMap)) {
       headers[headersMap[key][0]] = headersMap[key][1];
     }
   }
@@ -458,8 +451,8 @@ function processHeader(self, state, key, value, validate) {
     validateHeaderName(key);
   if (ArrayIsArray(value)) {
     if (value.length < 2 || !isCookieField(key)) {
-      for (var i = 0; i < value.length; i++)
-        storeHeader(self, state, key, value[i], validate);
+      for (keyValue of value)
+        storeHeader(self, state, key, keyValue, validate);
       return;
     }
     value = value.join('; ');
@@ -558,9 +551,7 @@ OutgoingMessage.prototype.getHeaders = function getHeaders() {
   const headers = this[kOutHeaders];
   const ret = ObjectCreate(null);
   if (headers) {
-    const keys = ObjectKeys(headers);
-    for (var i = 0; i < keys.length; ++i) {
-      const key = keys[i];
+    for (key of ObjectKeys(headers)) {
       const val = headers[key][1];
       ret[key] = val;
     }
@@ -697,11 +688,9 @@ function connectionCorkNT(conn) {
 
 OutgoingMessage.prototype.addTrailers = function addTrailers(headers) {
   this._trailer = '';
-  const keys = ObjectKeys(headers);
   const isArray = ArrayIsArray(headers);
   var field, value;
-  for (var i = 0, l = keys.length; i < l; i++) {
-    var key = keys[i];
+  for (key of ObjectKeys(headers)) {
     if (isArray) {
       field = headers[key][0];
       value = headers[key][1];
@@ -847,15 +836,13 @@ OutgoingMessage.prototype._flushOutput = function _flushOutput(socket) {
     socket.cork();
   }
 
-  const outputLength = this.outputData.length;
-  if (outputLength <= 0)
+  if (this.outputData.length <= 0)
     return undefined;
 
-  const outputData = this.outputData;
   socket.cork();
   let ret;
-  for (var i = 0; i < outputLength; i++) {
-    const { data, encoding, callback } = outputData[i];
+  for (outputDataItem of this.outputData) {
+    const { data, encoding, callback } = outputDataItem;
     ret = socket.write(data, encoding, callback);
   }
   socket.uncork();

From 3d87c3df77d6cb5a8afa73d19b633802647fb10c Mon Sep 17 00:00:00 2001
From: Trivikram Kamat <16024985+trivikr@users.noreply.github.com>
Date: Sat, 14 Dec 2019 09:00:04 -0500
Subject: [PATCH 05/10] http: added missing const in for loops

---
 lib/_http_agent.js    | 10 +++++-----
 lib/_http_client.js   |  2 +-
 lib/_http_outgoing.js | 16 ++++++++--------
 lib/_http_server.js   |  2 +-
 4 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/lib/_http_agent.js b/lib/_http_agent.js
index e47cbb2106fc8f..5e3298b594d949 100644
--- a/lib/_http_agent.js
+++ b/lib/_http_agent.js
@@ -146,7 +146,7 @@ function maybeEnableKeylog(eventName) {
       agent.emit('keylog', keylog, this);
     };
     // Existing sockets will start listening on keylog now.
-    for (socket of ObjectValues(this.sockets)) {
+    for (const socket of ObjectValues(this.sockets)) {
       socket.on('keylog', this[kOnKeylog]);
     }
   }
@@ -345,7 +345,7 @@ Agent.prototype.removeSocket = function removeSocket(s, options) {
   if (!s.writable)
     sets.push(this.freeSockets);
 
-  for (sockets of sets) {
+  for (const sockets of sets) {
     if (sockets[name]) {
       const index = sockets[name].indexOf(s);
       if (index !== -1) {
@@ -380,9 +380,9 @@ Agent.prototype.reuseSocket = function reuseSocket(socket, req) {
 };
 
 Agent.prototype.destroy = function destroy() {
-  for (set of [this.freeSockets, this.sockets]) {
-    for (key of ObjectKeys(set)) {
-      for (setName of set[key]) {
+  for (const set of [this.freeSockets, this.sockets]) {
+    for (const key of ObjectKeys(set)) {
+      for (const setName of set[key]) {
         setName.destroy();
       }
     }
diff --git a/lib/_http_client.js b/lib/_http_client.js
index 7f668b022ff774..932e6600bfa29a 100644
--- a/lib/_http_client.js
+++ b/lib/_http_client.js
@@ -230,7 +230,7 @@ function ClientRequest(input, options, cb) {
   const headersArray = ArrayIsArray(options.headers);
   if (!headersArray) {
     if (options.headers) {
-      for (key of ObjectKeys(options.headers)) {
+      for (const key of ObjectKeys(options.headers)) {
         this.setHeader(key, options.headers[key]);
       }
     }
diff --git a/lib/_http_outgoing.js b/lib/_http_outgoing.js
index 066edc58626eec..434c0dbc9d3f3e 100644
--- a/lib/_http_outgoing.js
+++ b/lib/_http_outgoing.js
@@ -165,7 +165,7 @@ ObjectDefineProperty(OutgoingMessage.prototype, '_headers', {
       this[kOutHeaders] = null;
     } else if (typeof val === 'object') {
       const headers = this[kOutHeaders] = ObjectCreate(null);
-      for (name of ObjectKeys(val)) {
+      for (const name of ObjectKeys(val)) {
         headers[name.toLowerCase()] = [name, val[name]];
       }
     }
@@ -186,7 +186,7 @@ ObjectDefineProperty(OutgoingMessage.prototype, '_headerNames', {
     const headers = this[kOutHeaders];
     if (headers !== null) {
       const out = ObjectCreate(null);
-      for (key of ObjectKeys(headers)) {
+      for (const key of ObjectKeys(headers)) {
         const val = headers[key][0];
         out[key] = val;
       }
@@ -199,7 +199,7 @@ ObjectDefineProperty(OutgoingMessage.prototype, '_headerNames', {
       const headers = this[kOutHeaders];
       if (!headers)
         return;
-      for (key of ObjectKeys(val)) {
+      for (const key of ObjectKeys(val)) {
         const header = headers[key];
         if (header)
           header[0] = val[key];
@@ -218,7 +218,7 @@ OutgoingMessage.prototype._renderHeaders = function _renderHeaders() {
   const headers = {};
 
   if (headersMap !== null) {
-    for (key of ObjectKeys(headersMap)) {
+    for (const key of ObjectKeys(headersMap)) {
       headers[headersMap[key][0]] = headersMap[key][1];
     }
   }
@@ -451,7 +451,7 @@ function processHeader(self, state, key, value, validate) {
     validateHeaderName(key);
   if (ArrayIsArray(value)) {
     if (value.length < 2 || !isCookieField(key)) {
-      for (keyValue of value)
+      for (const keyValue of value)
         storeHeader(self, state, key, keyValue, validate);
       return;
     }
@@ -551,7 +551,7 @@ OutgoingMessage.prototype.getHeaders = function getHeaders() {
   const headers = this[kOutHeaders];
   const ret = ObjectCreate(null);
   if (headers) {
-    for (key of ObjectKeys(headers)) {
+    for (const key of ObjectKeys(headers)) {
       const val = headers[key][1];
       ret[key] = val;
     }
@@ -690,7 +690,7 @@ OutgoingMessage.prototype.addTrailers = function addTrailers(headers) {
   this._trailer = '';
   const isArray = ArrayIsArray(headers);
   var field, value;
-  for (key of ObjectKeys(headers)) {
+  for (const key of ObjectKeys(headers)) {
     if (isArray) {
       field = headers[key][0];
       value = headers[key][1];
@@ -841,7 +841,7 @@ OutgoingMessage.prototype._flushOutput = function _flushOutput(socket) {
 
   socket.cork();
   let ret;
-  for (outputDataItem of this.outputData) {
+  for (const outputDataItem of this.outputData) {
     const { data, encoding, callback } = outputDataItem;
     ret = socket.write(data, encoding, callback);
   }
diff --git a/lib/_http_server.js b/lib/_http_server.js
index 173c43b370a2c8..3670a81800c8d9 100644
--- a/lib/_http_server.js
+++ b/lib/_http_server.js
@@ -262,7 +262,7 @@ function writeHead(statusCode, reason, obj) {
     // Slow-case: when progressive API and header fields are passed.
     let k;
     if (obj) {
-      for (key of ObjectKeys(obj)) {
+      for (const key of ObjectKeys(obj)) {
         k = key;
         if (k) this.setHeader(k, obj[k]);
       }

From 23fc285ced06e27f1249600387156c629b2c0224 Mon Sep 17 00:00:00 2001
From: Trivikram Kamat <16024985+trivikr@users.noreply.github.com>
Date: Sat, 14 Dec 2019 09:02:50 -0500
Subject: [PATCH 06/10] f rename keyValue -> valueItem

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

diff --git a/lib/_http_outgoing.js b/lib/_http_outgoing.js
index 434c0dbc9d3f3e..d1c8c7b57e12c9 100644
--- a/lib/_http_outgoing.js
+++ b/lib/_http_outgoing.js
@@ -451,8 +451,8 @@ function processHeader(self, state, key, value, validate) {
     validateHeaderName(key);
   if (ArrayIsArray(value)) {
     if (value.length < 2 || !isCookieField(key)) {
-      for (const keyValue of value)
-        storeHeader(self, state, key, keyValue, validate);
+      for (const valueItem of value)
+        storeHeader(self, state, key, valueItem, validate);
       return;
     }
     value = value.join('; ');

From c5c391602db21045dc7b483d54f0ee91bffa1559 Mon Sep 17 00:00:00 2001
From: Trivikram Kamat <16024985+trivikr@users.noreply.github.com>
Date: Sat, 14 Dec 2019 11:01:26 -0500
Subject: [PATCH 07/10] f destructure outputDataItem

---
 lib/_http_outgoing.js | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/lib/_http_outgoing.js b/lib/_http_outgoing.js
index d1c8c7b57e12c9..eb023b9401516c 100644
--- a/lib/_http_outgoing.js
+++ b/lib/_http_outgoing.js
@@ -841,8 +841,7 @@ OutgoingMessage.prototype._flushOutput = function _flushOutput(socket) {
 
   socket.cork();
   let ret;
-  for (const outputDataItem of this.outputData) {
-    const { data, encoding, callback } = outputDataItem;
+  for (const { data, encoding, callback } of this.outputData) {
     ret = socket.write(data, encoding, callback);
   }
   socket.uncork();

From 8d435801647cc57a6b14be4b484c1bb3de781413 Mon Sep 17 00:00:00 2001
From: Trivikram Kamat <16024985+trivikr@users.noreply.github.com>
Date: Sat, 14 Dec 2019 18:39:10 -0500
Subject: [PATCH 08/10] Revert "http: for of in lib/_http_client.js"

This reverts commit 63f73b9a8ffe7ef8f03058460751ffcf329bb5b3.
---
 lib/_http_client.js | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/_http_client.js b/lib/_http_client.js
index 932e6600bfa29a..9c5b18bc21e1f2 100644
--- a/lib/_http_client.js
+++ b/lib/_http_client.js
@@ -230,7 +230,11 @@ function ClientRequest(input, options, cb) {
   const headersArray = ArrayIsArray(options.headers);
   if (!headersArray) {
     if (options.headers) {
-      for (const key of ObjectKeys(options.headers)) {
+      const keys = ObjectKeys(options.headers);
+      // Retain for(;;) loop for performance reasons
+      // Refs: https://github.com/nodejs/node/pull/30958
+      for (let i = 0; i < keys.length; i++) {
+        const key = keys[i];
         this.setHeader(key, options.headers[key]);
       }
     }

From c2f4695d1f19b5841a162c92e4e041545a782186 Mon Sep 17 00:00:00 2001
From: Trivikram Kamat <16024985+trivikr@users.noreply.github.com>
Date: Sat, 14 Dec 2019 18:52:02 -0500
Subject: [PATCH 09/10] Revert "http: for of in lib/_http_server.js"

This reverts commit 3ba1da23078b7ffd3a73a164e807095e42a3e837.
---
 lib/_http_server.js | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/lib/_http_server.js b/lib/_http_server.js
index 3670a81800c8d9..af860c88064b4e 100644
--- a/lib/_http_server.js
+++ b/lib/_http_server.js
@@ -262,8 +262,11 @@ function writeHead(statusCode, reason, obj) {
     // Slow-case: when progressive API and header fields are passed.
     let k;
     if (obj) {
-      for (const key of ObjectKeys(obj)) {
-        k = key;
+      const keys = ObjectKeys(obj);
+      // Retain for(;;) loop for performance reasons
+      // Refs: https://github.com/nodejs/node/pull/30958
+      for (let i = 0; i < keys.length; i++) {
+        k = keys[i];
         if (k) this.setHeader(k, obj[k]);
       }
     }

From 17049d56621869d8776a922d5e56b6c5ec35be7b Mon Sep 17 00:00:00 2001
From: Trivikram Kamat <16024985+trivikr@users.noreply.github.com>
Date: Sat, 14 Dec 2019 18:55:08 -0500
Subject: [PATCH 10/10] Revert "http: for of in lib/_http_outgoing.js"

This reverts commit b4b4d3da28e841eb986ff39840b0b763f3bd5569.
---
 lib/_http_outgoing.js | 54 +++++++++++++++++++++++++++++++++----------
 1 file changed, 42 insertions(+), 12 deletions(-)

diff --git a/lib/_http_outgoing.js b/lib/_http_outgoing.js
index eb023b9401516c..36d3054eab0663 100644
--- a/lib/_http_outgoing.js
+++ b/lib/_http_outgoing.js
@@ -165,7 +165,11 @@ ObjectDefineProperty(OutgoingMessage.prototype, '_headers', {
       this[kOutHeaders] = null;
     } else if (typeof val === 'object') {
       const headers = this[kOutHeaders] = ObjectCreate(null);
-      for (const name of ObjectKeys(val)) {
+      const keys = ObjectKeys(val);
+      // Retain for(;;) loop for performance reasons
+      // Refs: https://github.com/nodejs/node/pull/30958
+      for (var i = 0; i < keys.length; ++i) {
+        const name = keys[i];
         headers[name.toLowerCase()] = [name, val[name]];
       }
     }
@@ -186,7 +190,11 @@ ObjectDefineProperty(OutgoingMessage.prototype, '_headerNames', {
     const headers = this[kOutHeaders];
     if (headers !== null) {
       const out = ObjectCreate(null);
-      for (const key of ObjectKeys(headers)) {
+      const keys = ObjectKeys(headers);
+      // Retain for(;;) loop for performance reasons
+      // Refs: https://github.com/nodejs/node/pull/30958
+      for (var i = 0; i < keys.length; ++i) {
+        const key = keys[i];
         const val = headers[key][0];
         out[key] = val;
       }
@@ -199,10 +207,13 @@ ObjectDefineProperty(OutgoingMessage.prototype, '_headerNames', {
       const headers = this[kOutHeaders];
       if (!headers)
         return;
-      for (const key of ObjectKeys(val)) {
-        const header = headers[key];
+      const keys = ObjectKeys(val);
+      // Retain for(;;) loop for performance reasons
+      // Refs: https://github.com/nodejs/node/pull/30958
+      for (var i = 0; i < keys.length; ++i) {
+        const header = headers[keys[i]];
         if (header)
-          header[0] = val[key];
+          header[0] = val[keys[i]];
       }
     }
   }, 'OutgoingMessage.prototype._headerNames is deprecated', 'DEP0066')
@@ -218,7 +229,11 @@ OutgoingMessage.prototype._renderHeaders = function _renderHeaders() {
   const headers = {};
 
   if (headersMap !== null) {
-    for (const key of ObjectKeys(headersMap)) {
+    const keys = ObjectKeys(headersMap);
+    // Retain for(;;) loop for performance reasons
+    // Refs: https://github.com/nodejs/node/pull/30958
+    for (var i = 0, l = keys.length; i < l; i++) {
+      const key = keys[i];
       headers[headersMap[key][0]] = headersMap[key][1];
     }
   }
@@ -451,8 +466,10 @@ function processHeader(self, state, key, value, validate) {
     validateHeaderName(key);
   if (ArrayIsArray(value)) {
     if (value.length < 2 || !isCookieField(key)) {
-      for (const valueItem of value)
-        storeHeader(self, state, key, valueItem, validate);
+      // Retain for(;;) loop for performance reasons
+      // Refs: https://github.com/nodejs/node/pull/30958
+      for (var i = 0; i < value.length; i++)
+        storeHeader(self, state, key, value[i], validate);
       return;
     }
     value = value.join('; ');
@@ -551,7 +568,11 @@ OutgoingMessage.prototype.getHeaders = function getHeaders() {
   const headers = this[kOutHeaders];
   const ret = ObjectCreate(null);
   if (headers) {
-    for (const key of ObjectKeys(headers)) {
+    const keys = ObjectKeys(headers);
+    // Retain for(;;) loop for performance reasons
+    // Refs: https://github.com/nodejs/node/pull/30958
+    for (var i = 0; i < keys.length; ++i) {
+      const key = keys[i];
       const val = headers[key][1];
       ret[key] = val;
     }
@@ -688,9 +709,13 @@ function connectionCorkNT(conn) {
 
 OutgoingMessage.prototype.addTrailers = function addTrailers(headers) {
   this._trailer = '';
+  const keys = ObjectKeys(headers);
   const isArray = ArrayIsArray(headers);
   var field, value;
-  for (const key of ObjectKeys(headers)) {
+  // Retain for(;;) loop for performance reasons
+  // Refs: https://github.com/nodejs/node/pull/30958
+  for (var i = 0, l = keys.length; i < l; i++) {
+    var key = keys[i];
     if (isArray) {
       field = headers[key][0];
       value = headers[key][1];
@@ -836,12 +861,17 @@ OutgoingMessage.prototype._flushOutput = function _flushOutput(socket) {
     socket.cork();
   }
 
-  if (this.outputData.length <= 0)
+  const outputLength = this.outputData.length;
+  if (outputLength <= 0)
     return undefined;
 
+  const outputData = this.outputData;
   socket.cork();
   let ret;
-  for (const { data, encoding, callback } of this.outputData) {
+  // Retain for(;;) loop for performance reasons
+  // Refs: https://github.com/nodejs/node/pull/30958
+  for (var i = 0; i < outputLength; i++) {
+    const { data, encoding, callback } = outputData[i];
     ret = socket.write(data, encoding, callback);
   }
   socket.uncork();