Fix dev

frontend/src/scripts/configuration.ts

@@ -6,7 +6,21 @@
  * only shows a server once it responds, so listing an offline origin here is
  * harmless. Add or remove origins as you deploy more server containers.
  */
-const servers: Array<string> = ['https://server.decla.red'];
+const productionServers: Array<string> = ['https://declared.schmelczer.dev'];
+
+/**
+ * When the page is served from localhost (i.e. the webpack-dev-server), also
+ * offer the local backend so a `npm start` server can be joined during
+ * development. The backend's default port is 3000 (see backend/src/options.ts).
+ * In production the hostname is `declared.schmelczer.dev`, so this never leaks.
+ */
+const isDevelopment =
+  typeof location !== 'undefined' &&
+  (location.hostname === 'localhost' || location.hostname === '127.0.0.1');
+
+const servers: Array<string> = isDevelopment
+  ? [`http://${location.hostname}:3000`, ...productionServers]
+  : productionServers;
 
 export abstract class Configuration {
   public static async initialize(): Promise<void> {