Only calculate the language on load.

src/card.ts

@@ -1159,7 +1159,7 @@ class FrigateCard extends LitElement {
       .initializeMultipleIfNecessary({
         // Caution: Ensure nothing in this set of initializers requires
         // languages since they will not yet have been initialized.
-        [InitializationAspect.LANGUAGES]: async () => loadLanguages,
+        [InitializationAspect.LANGUAGES]: async () => loadLanguages(hass),
         [InitializationAspect.SIDE_LOAD_ELEMENTS]: async () =>
           sideLoadHomeAssistantElements,
       })

src/localize/localize.ts

@@ -1,57 +1,66 @@
+import { HomeAssistant } from 'custom-card-helpers';
 import * as en from './languages/en.json';
 
+const DEFAULT_LANG = 'en' as const;
+
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 const languages: Record<string, any> = {
   // English as always loaded as it's the fallback language that will be used
   // when translations are not found or before they are loaded (via
   // loadLanguages()).
-  en: en,
-}
+  [DEFAULT_LANG]: en,
+};
+
+// The language is calculated and stored once, then re-used to avoid needing to
+// repeat the lookups and to ensure minimal information needs to be plumbed
+// through on each localization call.
+let frigateCardLanguage: string | undefined;
 
 /**
  * Get the configured language.
  */
-export function getLanguage(): string {
-  const canonicalizeLanguage = (language?: string | null): string | null => {
-    if (!language) {
-      return null;
-    }
+export function getLanguage(hass?: HomeAssistant): string {
+  const canonicalizeLanguage = (language: string): string => {
     return language.replace('-', '_');
   };
 
-  // Try the HA language first...
-  let lang: string | null = null;
-  const HALanguage = localStorage.getItem('selectedLanguage');
-  if (HALanguage) {
-    const selectedLanguage = canonicalizeLanguage(JSON.parse(HALanguage));
-    if (selectedLanguage) {
-      lang = selectedLanguage;
-    }
+  // Try the hass language first...
+  const hassLanguage = hass?.language ?? hass?.selectedLanguage;
+  if (hassLanguage) {
+    return canonicalizeLanguage(hassLanguage);
+  }
+
+  // Then the language that hass may have stored locally.
+  const storageLanguage = localStorage.getItem('selectedLanguage');
+  if (storageLanguage) {
+    return canonicalizeLanguage(JSON.parse(storageLanguage));
   }
 
   // Then fall back to the browser language.
-  if (!lang) {
-    for (const language of navigator.languages) {
-      const canonicalLanguage = canonicalizeLanguage(language);
-      if (canonicalLanguage && canonicalLanguage in languages) {
-        lang = language;
-      }
+  for (const language of navigator.languages) {
+    const canonicalLanguage = canonicalizeLanguage(language);
+    if (canonicalLanguage && canonicalLanguage in languages) {
+      return canonicalLanguage;
     }
   }
-  return lang || 'en';
+  return DEFAULT_LANG;
 }
 
 /**
  * Load required languages.
  */
-export const loadLanguages = async (): Promise<void> => {
-  const lang = getLanguage();
+export const loadLanguages = async (hass: HomeAssistant): Promise<void> => {
+  const lang = getLanguage(hass);
   if (lang === 'it') {
     languages['it'] = await import('./languages/it.json');
   } else if (lang === 'pt_BR') {
     languages['pt_BR'] = await import('./languages/pt-BR.json');
   }
-}
+
+  if (lang) {
+    frigateCardLanguage = lang;
+  }
+};
 
 /**
  * Get a localized version of a given string key.
@@ -61,16 +70,16 @@ export const loadLanguages = async (): Promise<void> => {
  * @returns
  */
 export function localize(string: string, search = '', replace = ''): string {
-  const lang = getLanguage();
   let translated = '';
 
   try {
-    translated = string.split('.').reduce((o, i) => o[i], languages[lang]);
-  } catch (_) {
-  }
+    translated = string
+      .split('.')
+      .reduce((o, i) => o[i], languages[frigateCardLanguage ?? DEFAULT_LANG]);
+  } catch (_) {}
 
   if (!translated) {
-    translated = string.split('.').reduce((o, i) => o[i], languages['en']);
+    translated = string.split('.').reduce((o, i) => o[i], languages[DEFAULT_LANG]);
   }
 
   if (search !== '' && replace !== '') {