lib: improve for-loop in master.js

Author: gengjiawen

lib/internal/cluster/master.js

@@ -80,10 +80,7 @@ cluster.setupMaster = function(options) {
     if (message.cmd !== 'NODE_DEBUG_ENABLED')
       return;
 
-    var key;
-    for (key in cluster.workers) {
-      const worker = cluster.workers[key];
-
+    for (const worker of Object.values(cluster.workers)) {
       if (worker.state === 'online' || worker.state === 'listening') {
         process._debugProcess(worker.process.pid);
       } else {
@@ -227,11 +224,10 @@ cluster.disconnect = function(cb) {
   if (workers.length === 0) {
     process.nextTick(() => intercom.emit('disconnect'));
   } else {
-    for (var key in workers) {
-      key = workers[key];
-
-      if (cluster.workers[key].isConnected())
-        cluster.workers[key].disconnect();
+    for (const worker of Object.values(cluster.workers)) {
+      if (worker.isConnected()) {
+        worker.disconnect();
+      }
     }
   }