lib: replace var with let/const

PR-URL: #30391
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

lib/events.js

@@ -37,7 +37,7 @@ const {
   }
 } = primordials;
 
-var spliceOne;
+let spliceOne;
 
 const {
   kEnhanceStackBeforeInspector,
@@ -70,7 +70,7 @@ EventEmitter.prototype._maxListeners = undefined;
 
 // By default EventEmitters will print a warning if more than 10 listeners are
 // added to it. This is a useful default which helps finding memory leaks.
-var defaultMaxListeners = 10;
+let defaultMaxListeners = 10;
 
 function checkListener(listener) {
   if (typeof listener !== 'function') {
@@ -127,7 +127,7 @@ EventEmitter.prototype.getMaxListeners = function getMaxListeners() {
 // Returns the length and line number of the first sequence of `a` that fully
 // appears in `b` with a length of at least 4.
 function identicalSequenceRange(a, b) {
-  for (var i = 0; i < a.length - 3; i++) {
+  for (let i = 0; i < a.length - 3; i++) {
     // Find the first entry of b that matches the current entry of a.
     const pos = b.indexOf(a[i]);
     if (pos !== -1) {
@@ -224,17 +224,17 @@ EventEmitter.prototype.emit = function emit(type, ...args) {
   } else {
     const len = handler.length;
     const listeners = arrayClone(handler, len);
-    for (var i = 0; i < len; ++i)
+    for (let i = 0; i < len; ++i)
       ReflectApply(listeners[i], this, args);
   }
 
   return true;
 };
 
 function _addListener(target, type, listener, prepend) {
-  var m;
-  var events;
-  var existing;
+  let m;
+  let events;
+  let existing;
 
   checkListener(listener);
 
@@ -363,7 +363,7 @@ EventEmitter.prototype.removeListener =
       } else if (typeof list !== 'function') {
         let position = -1;
 
-        for (var i = list.length - 1; i >= 0; i--) {
+        for (let i = list.length - 1; i >= 0; i--) {
           if (list[i] === listener || list[i].listener === listener) {
             originalListener = list[i].listener;
             position = i;
@@ -432,7 +432,7 @@ EventEmitter.prototype.removeAllListeners =
         this.removeListener(type, listeners);
       } else if (listeners !== undefined) {
         // LIFO order
-        for (var i = listeners.length - 1; i >= 0; i--) {
+        for (let i = listeners.length - 1; i >= 0; i--) {
           this.removeListener(type, listeners[i]);
         }
       }
@@ -496,14 +496,14 @@ EventEmitter.prototype.eventNames = function eventNames() {
 
 function arrayClone(arr, n) {
   const copy = new Array(n);
-  for (var i = 0; i < n; ++i)
+  for (let i = 0; i < n; ++i)
     copy[i] = arr[i];
   return copy;
 }
 
 function unwrapListeners(arr) {
   const ret = new Array(arr.length);
-  for (var i = 0; i < ret.length; ++i) {
+  for (let i = 0; i < ret.length; ++i) {
     ret[i] = arr[i].listener || arr[i];
   }
   return ret;

lib/internal/process/task_queues.js

@@ -105,15 +105,15 @@ function nextTick(callback) {
   if (process._exiting)
     return;
 
-  var args;
+  let args;
   switch (arguments.length) {
     case 1: break;
     case 2: args = [arguments[1]]; break;
     case 3: args = [arguments[1], arguments[2]]; break;
     case 4: args = [arguments[1], arguments[2], arguments[3]]; break;
     default:
       args = new Array(arguments.length - 1);
-      for (var i = 1; i < arguments.length; i++)
+      for (let i = 1; i < arguments.length; i++)
         args[i - 1] = arguments[i];
   }