Refactor webpack-dev-server middleware application logic

lib/Server.js

@@ -552,6 +552,35 @@ class Server {
           searchParams.set("password", webSocketURL.password);
         }
 
+        // Initialize an array to keep track of applied middleware
+        const appliedMiddleware = [];
+
+        // Function to apply middleware only once
+        function applyMiddlewareOnce(middleware) {
+          // Check if the middleware has already been applied
+          if (!appliedMiddleware.includes(middleware)) {
+            // Apply the middleware
+            this.app.use(middleware);
+
+            // Add the middleware to the applied middleware array
+            appliedMiddleware.push(middleware);
+          }
+        }
+
+        // Apply middleware for each feature only once
+        if (this.options.proxy) {
+          applyMiddlewareOnce.call(this, proxyMiddleware);
+        }
+
+        if (this.options.contentBase !== false) {
+          applyMiddlewareOnce.call(this, contentBaseMiddleware);
+        }
+
+        if (this.options.historyApiFallback) {
+          applyMiddlewareOnce.call(this, historyApiFallbackMiddleware);
+        }
+
+
         /** @type {string} */
         let hostname;