benchmark: use let instead of var in util

PR-URL: https://github.com/nodejs/node/pull/31794
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

benchmark/util/inspect-array.js

@@ -15,8 +15,8 @@ const bench = common.createBenchmark(main, {
 });
 
 function main({ n, len, type }) {
-  var arr = Array(len);
-  var i, opts;
+  let arr = Array(len);
+  let opts;
 
   switch (type) {
     case 'denseArray_showHidden':
@@ -29,14 +29,14 @@ function main({ n, len, type }) {
     case 'sparseArray':
       break;
     case 'mixedArray':
-      for (i = 0; i < n; i += 2)
+      for (let i = 0; i < n; i += 2)
         arr[i] = i;
       break;
     default:
       throw new Error(`Unsupported type ${type}`);
   }
   bench.start();
-  for (i = 0; i < n; i++) {
+  for (let i = 0; i < n; i++) {
     util.inspect(arr, opts);
   }
   bench.end(n);

benchmark/util/inspect.js

@@ -37,7 +37,7 @@ function benchmark(n, obj, options) {
 }
 
 function main({ method, n, option }) {
-  var obj;
+  let obj;
   const options = opts[option];
   switch (method) {
     case 'Object':

benchmark/util/normalize-encoding.js

@@ -46,11 +46,11 @@ function getInput(input) {
 function main({ input, n }) {
   const { normalizeEncoding } = require('internal/util');
   const inputs = getInput(input);
-  var noDead = '';
+  let noDead = '';
 
   bench.start();
-  for (var i = 0; i < n; ++i) {
-    for (var j = 0; j < inputs.length; ++j) {
+  for (let i = 0; i < n; ++i) {
+    for (let j = 0; j < inputs.length; ++j) {
       noDead = normalizeEncoding(inputs[j]);
     }
   }