http: use for...of in http library code

PR-URL: https://github.com/nodejs/node/pull/30958
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

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 (const 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 (const 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 (const set of [this.freeSockets, this.sockets]) {
+    for (const key of ObjectKeys(set)) {
+      for (const setName of set[key]) {
+        setName.destroy();
       }
     }
   }

lib/_http_client.js

@@ -231,6 +231,8 @@ function ClientRequest(input, options, cb) {
   if (!headersArray) {
     if (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]);

lib/_http_outgoing.js

@@ -166,6 +166,8 @@ ObjectDefineProperty(OutgoingMessage.prototype, '_headers', {
     } else if (typeof val === 'object') {
       const headers = this[kOutHeaders] = ObjectCreate(null);
       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]];
@@ -189,6 +191,8 @@ ObjectDefineProperty(OutgoingMessage.prototype, '_headerNames', {
     if (headers !== null) {
       const out = ObjectCreate(null);
       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];
@@ -204,6 +208,8 @@ ObjectDefineProperty(OutgoingMessage.prototype, '_headerNames', {
       if (!headers)
         return;
       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)
@@ -224,6 +230,8 @@ OutgoingMessage.prototype._renderHeaders = function _renderHeaders() {
 
   if (headersMap !== null) {
     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];
@@ -458,6 +466,8 @@ function processHeader(self, state, key, value, validate) {
     validateHeaderName(key);
   if (ArrayIsArray(value)) {
     if (value.length < 2 || !isCookieField(key)) {
+      // 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;
@@ -559,6 +569,8 @@ OutgoingMessage.prototype.getHeaders = function getHeaders() {
   const ret = ObjectCreate(null);
   if (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];
@@ -700,6 +712,8 @@ OutgoingMessage.prototype.addTrailers = function addTrailers(headers) {
   const keys = ObjectKeys(headers);
   const isArray = ArrayIsArray(headers);
   var field, value;
+  // 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) {
@@ -854,6 +868,8 @@ OutgoingMessage.prototype._flushOutput = function _flushOutput(socket) {
   const outputData = this.outputData;
   socket.cork();
   let ret;
+  // 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);

lib/_http_server.js

@@ -263,6 +263,8 @@ function writeHead(statusCode, reason, obj) {
     let k;
     if (obj) {
       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]);