refactor: extract typed frontend core utilities

src/trx-client/trx-frontend/trx-frontend-http/frontend/src/app.js

@@ -9,6 +9,8 @@ import {
   latLonToMaidenhead,
   locatorToLatLon,
 } from "./core/geo.js";
+import { escapeHtml as escapeMapHtml } from "./core/dom.js";
+import { loadSetting, saveSetting } from "./core/settings.js";
 
 // --- Decoder registry (fetched from /decoders on load) ---
 /** @type {Array<{id:string,label:string,activation:string,active_modes:string[],background_decode:boolean,bookmark_selectable:boolean}>} */
@@ -75,25 +77,6 @@ function hideUnsupportedDecoderTabs() {
   });
 }
 
-// --- Persistent settings (localStorage) ---
-const STORAGE_PREFIX = "trx_";
-function saveSetting(key, value) {
-  try { localStorage.setItem(STORAGE_PREFIX + key, JSON.stringify(value)); } catch(e) {}
-}
-function loadSetting(key, fallback) {
-  try {
-    const v = localStorage.getItem(STORAGE_PREFIX + key);
-    return v !== null ? JSON.parse(v) : fallback;
-  } catch(e) { return fallback; }
-}
-function escapeMapHtml(input) {
-  return String(input)
-    .replaceAll("&", "&amp;")
-    .replaceAll("<", "&lt;")
-    .replaceAll(">", "&gt;")
-    .replaceAll("\"", "&quot;");
-}
-
 // --- Authentication ---
 let authRole = null;  // null (not authenticated), "rx" (read-only), or "control" (full access)
 let authEnabled = true;

src/trx-client/trx-frontend/trx-frontend-http/frontend/src/core/dom.ts

@@ -0,0 +1,11 @@
+// SPDX-FileCopyrightText: 2026 Stan Grams <sjg@haxx.space>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+export function escapeHtml(input: unknown): string {
+  return String(input)
+    .replaceAll("&", "&amp;")
+    .replaceAll("<", "&lt;")
+    .replaceAll(">", "&gt;")
+    .replaceAll("\"", "&quot;");
+}

src/trx-client/trx-frontend/trx-frontend-http/frontend/src/core/settings.ts

@@ -0,0 +1,22 @@
+// SPDX-FileCopyrightText: 2026 Stan Grams <sjg@haxx.space>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+const STORAGE_PREFIX = "trx_";
+
+export function saveSetting(key: string, value: unknown): void {
+  try {
+    localStorage.setItem(`${STORAGE_PREFIX}${key}`, JSON.stringify(value));
+  } catch {
+    // Storage can be unavailable in private browsing or under a strict policy.
+  }
+}
+
+export function loadSetting<T>(key: string, fallback: T): T {
+  try {
+    const value = localStorage.getItem(`${STORAGE_PREFIX}${key}`);
+    return value === null ? fallback : JSON.parse(value) as T;
+  } catch {
+    return fallback;
+  }
+}