diff --git a/lib/Server.js b/lib/Server.js
index 460471bd68..d966ea83a7 100644
--- a/lib/Server.js
+++ b/lib/Server.js
@@ -66,22 +66,8 @@ class Server {
 
     this.log = _log || createLogger(options);
 
-    // set serverMode default
-    if (this.options.serverMode === undefined) {
-      this.options.serverMode = 'sockjs';
-    } else {
-      this.log.warn(
-        'serverMode is an experimental option, meaning its usage could potentially change without warning'
-      );
-    }
-    // set clientMode default
-    if (this.options.clientMode === undefined) {
-      this.options.clientMode = 'sockjs';
-    } else {
-      this.log.warn(
-        'clientMode is an experimental option, meaning its usage could potentially change without warning'
-      );
-    }
+    // set client and server default mode
+    this.setDefaultMode();
 
     updateCompiler(this.compiler, this.options);
 
@@ -153,6 +139,18 @@ class Server {
     }, this);
   }
 
+  setDefaultMode() {
+    ['serverMode', 'clientMode'].forEach((mode) => {
+      if (this.options[mode] === undefined) {
+        this.options[mode] = 'sockjs';
+      } else {
+        this.log.warn(
+          `${mode} is an experimental option, meaning its usage could potentially change without warning`
+        );
+      }
+    });
+  }
+
   setupProgressPlugin() {
     // for CLI output
     new webpack.ProgressPlugin({
@@ -292,14 +290,12 @@ class Server {
      * ]
      */
     this.options.proxy.forEach((proxyConfigOrCallback) => {
-      let proxyConfig;
       let proxyMiddleware;
 
-      if (typeof proxyConfigOrCallback === 'function') {
-        proxyConfig = proxyConfigOrCallback();
-      } else {
-        proxyConfig = proxyConfigOrCallback;
-      }
+      const proxyConfig =
+        typeof proxyConfigOrCallback === 'function'
+          ? proxyConfigOrCallback()
+          : proxyConfigOrCallback;
 
       proxyMiddleware = getProxyMiddleware(proxyConfig);