Mapping /admin as /admin.html in devMode

config/webpackDevServer.config.ts

@@ -59,9 +59,8 @@ export default function({
     },
     overlay: false,
     historyApiFallback: {
-      // Paths with dots should still use the history fallback.
-      // See https://github.com/facebookincubator/create-react-app/issues/387.
       disableDotRule: true,
+      rewrites: [{ from: /^\/admin/, to: "/admin.html" }],
     },
     public: allowedHost,
     index: "embed.html",