benchmark: use let instead of var in crypto

benchmark/crypto/aes-gcm-throughput.js

@@ -25,7 +25,7 @@ function AEAD_Bench(cipher, message, associate_data, key, iv, n, len) {
   const bits = written * 8;
   const mbits = bits / (1024 * 1024);
 
-  for (var i = 0; i < n; i++) {
+  for (let i = 0; i < n; i++) {
     const alice = crypto.createCipheriv(cipher, key, iv);
     alice.setAAD(associate_data);
     const enc = alice.update(message);

benchmark/crypto/cipher-stream.js

@@ -38,8 +38,8 @@ function main({ api, cipher, type, len, writes }) {
   const alice_cipher = crypto.createCipher(cipher, alice_secret);
   const bob_cipher = crypto.createDecipher(cipher, bob_secret);
 
-  var message;
-  var encoding;
+  let message;
+  let encoding;
   switch (type) {
     case 'asc':
       message = 'a'.repeat(len);
@@ -65,7 +65,7 @@ function main({ api, cipher, type, len, writes }) {
 }
 
 function streamWrite(alice, bob, message, encoding, writes) {
-  var written = 0;
+  let written = 0;
   bob.on('data', (c) => {
     written += c.length;
   });
@@ -86,9 +86,9 @@ function streamWrite(alice, bob, message, encoding, writes) {
 }
 
 function legacyWrite(alice, bob, message, encoding, writes) {
-  var written = 0;
-  var enc, dec;
-  for (var i = 0; i < writes; i++) {
+  let written = 0;
+  let enc, dec;
+  for (let i = 0; i < writes; i++) {
     enc = alice.update(message, encoding);
     dec = bob.update(enc);
     written += dec.length;

benchmark/crypto/get-ciphers.js

@@ -9,7 +9,7 @@ const bench = common.createBenchmark(main, {
 
 function main({ n, v }) {
   const method = require(v).getCiphers;
-  var i = 0;
+  let i = 0;
   // First call to getCiphers will dominate the results
   if (n > 1) {
     for (; i < n; i++)

benchmark/crypto/hash-stream-creation.js

@@ -20,8 +20,8 @@ function main({ api, type, len, out, writes, algo }) {
     api = 'legacy';
   }
 
-  var message;
-  var encoding;
+  let message;
+  let encoding;
   switch (type) {
     case 'asc':
       message = 'a'.repeat(len);
@@ -52,7 +52,7 @@ function legacyWrite(algo, message, encoding, writes, len, outEnc) {
   while (writes-- > 0) {
     const h = crypto.createHash(algo);
     h.update(message, encoding);
-    var res = h.digest(outEnc);
+    let res = h.digest(outEnc);
 
     // Include buffer creation costs for older versions
     if (outEnc === 'buffer' && typeof res === 'string')

benchmark/crypto/hash-stream-throughput.js

@@ -19,8 +19,8 @@ function main({ api, type, len, algo, writes }) {
     api = 'legacy';
   }
 
-  var message;
-  var encoding;
+  let message;
+  let encoding;
   switch (type) {
     case 'asc':
       message = 'a'.repeat(len);

benchmark/crypto/rsa-encrypt-decrypt-throughput.js

@@ -35,7 +35,7 @@ function StreamWrite(algo, keylen, message, n, len) {
 
   const privateKey = RSA_PrivatePem[keylen];
   const publicKey = RSA_PublicPem[keylen];
-  for (var i = 0; i < n; i++) {
+  for (let i = 0; i < n; i++) {
     const enc = crypto.privateEncrypt(privateKey, message);
     crypto.publicDecrypt(publicKey, enc);
   }