benchmark: use let instead of var in child_process

PR-URL: #31043
Reviewed-By: Rich Trott <[email protected]>
Reviewed-By: Ruben Bridgewater <[email protected]>

Author: dnlup

benchmark/child_process/child-process-exec-stdout.js

@@ -19,7 +19,7 @@ function childProcessExecStdout({ dur, len }) {
   const cmd = `yes "${'.'.repeat(len)}"`;
   const child = exec(cmd, { 'stdio': ['ignore', 'pipe', 'ignore'] });
 
-  var bytes = 0;
+  let bytes = 0;
   child.stdout.on('data', (msg) => {
     bytes += msg.length;
   });

benchmark/child_process/child-process-read-ipc.js

@@ -26,7 +26,7 @@ if (process.argv[2] === 'child') {
     const child = spawn(process.argv[0],
                         [process.argv[1], 'child', len], options);
 
-    var bytes = 0;
+    let bytes = 0;
     child.on('message', (msg) => { bytes += msg.length; });
 
     setTimeout(() => {

benchmark/child_process/child-process-read.js

@@ -24,7 +24,7 @@ function main({ dur, len }) {
   const options = { 'stdio': ['ignore', 'pipe', 'ignore'] };
   const child = child_process.spawn('yes', [msg], options);
 
-  var bytes = 0;
+  let bytes = 0;
   child.stdout.on('data', (msg) => {
     bytes += msg.length;
   });