dgram: changed 'var' to 'let' and 'const'

PR-URL: #28357
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

lib/dgram.js

@@ -79,15 +79,15 @@ const RECV_BUFFER = true;
 const SEND_BUFFER = false;
 
 // Lazily loaded
-var cluster = null;
+let cluster = null;
 
 const errnoException = errors.errnoException;
 const exceptionWithHostPort = errors.exceptionWithHostPort;
 
 
 function Socket(type, listener) {
   EventEmitter.call(this);
-  var lookup;
+  let lookup;
   let recvBufferSize;
   let sendBufferSize;
 
@@ -262,8 +262,8 @@ Socket.prototype.bind = function(port_, address_ /* , callback */) {
     return this;
   }
 
-  var address;
-  var exclusive;
+  let address;
+  let exclusive;
 
   if (port !== null && typeof port === 'object') {
     address = port.address || '';
@@ -293,7 +293,7 @@ Socket.prototype.bind = function(port_, address_ /* , callback */) {
     if (!cluster)
       cluster = require('cluster');
 
-    var flags = 0;
+    let flags = 0;
     if (state.reuseAddr)
       flags |= UV_UDP_REUSEADDR;
     if (state.ipv6Only)
@@ -318,7 +318,7 @@ Socket.prototype.bind = function(port_, address_ /* , callback */) {
 
       const err = state.handle.bind(ip, port || 0, flags);
       if (err) {
-        var ex = exceptionWithHostPort(err, 'bind', ip, port);
+        const ex = exceptionWithHostPort(err, 'bind', ip, port);
         this.emit('error', ex);
         state.bindState = BIND_STATE_UNBOUND;
         // Todo: close?
@@ -467,8 +467,8 @@ function sliceBuffer(buffer, offset, length) {
 function fixBufferList(list) {
   const newlist = new Array(list.length);
 
-  for (var i = 0, l = list.length; i < l; i++) {
-    var buf = list[i];
+  for (let i = 0, l = list.length; i < l; i++) {
+    const buf = list[i];
     if (typeof buf === 'string')
       newlist[i] = Buffer.from(buf);
     else if (!isUint8Array(buf))
@@ -514,7 +514,7 @@ function clearQueue() {
   state.queue = undefined;
 
   // Flush the send queue.
-  for (var i = 0; i < queue.length; i++)
+  for (let i = 0; i < queue.length; i++)
     queue[i]();
 }
 
@@ -732,8 +732,8 @@ Socket.prototype.remoteAddress = function() {
   if (state.connectState !== CONNECT_STATE_CONNECTED)
     throw new ERR_SOCKET_DGRAM_NOT_CONNECTED();
 
-  var out = {};
-  var err = state.handle.getpeername(out);
+  const out = {};
+  const err = state.handle.getpeername(out);
   if (err)
     throw errnoException(err, 'getpeername');