lib: change var to let in internal/streams

PR-URL: #30430
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Denys Otrishko <shishugi@gmail.com>

lib/internal/streams/buffer_list.js

@@ -48,8 +48,8 @@ module.exports = class BufferList {
   join(s) {
     if (this.length === 0)
       return '';
-    var p = this.head;
-    var ret = '' + p.data;
+    let p = this.head;
+    let ret = '' + p.data;
     while (p = p.next)
       ret += s + p.data;
     return ret;
@@ -59,8 +59,8 @@ module.exports = class BufferList {
     if (this.length === 0)
       return Buffer.alloc(0);
     const ret = Buffer.allocUnsafe(n >>> 0);
-    var p = this.head;
-    var i = 0;
+    let p = this.head;
+    let i = 0;
     while (p) {
       ret.set(p.data, i);
       i += p.data.length;

lib/internal/streams/legacy.js

@@ -36,7 +36,7 @@ Stream.prototype.pipe = function(dest, options) {
     source.on('close', onclose);
   }
 
-  var didOnEnd = false;
+  let didOnEnd = false;
   function onend() {
     if (didOnEnd) return;
     didOnEnd = true;