Move translation caching to i18next.js

packages/common/i18next.js

 import i18next from 'i18next';
 
+// global variable as cache for translations
+const translationCache = {};
+
+// fetches overrides for given language
+async function fetchOverridesByLanguage(overrides, lng) {
+  let result = await
+      fetch(overrides + lng +'/translation.json', {
+          headers: {'Content-Type': 'application/json'},
+      });
+  let json = await result.json();
+  return json;
+}
+
+// handles translation cache promises
+async function cacheOverrides(overridesFile, lng) {
+  // use global var as cache
+  if (translationCache[lng] === undefined) {
+    // get translation.json for each lang
+    let response = fetchOverridesByLanguage(overridesFile, lng);
+    translationCache[lng] = response;
+    return response;
+  } else {
+    return translationCache[lng];
+  }
+}
+
 /**
  * Like Intl.DateTimeFormat().format() but uses the current language as locale.
  *
@@ -135,21 +161,25 @@ export function setOverrides(i18n, element, overrides) {
  * @param {HTMLElement} element - The element at which the overrides are targeted
  * @param {object} overrides - The override data as promise
  */
-export async function setOverridesByPromise(i18n, element, overrides) {
+export async function setOverridesByGlobalCache(i18n, element) {
     // We add a special namespace which gets used with priority and falls back
     // to the original one. This way we an change the overrides at runtime
     // and can even remove them.
 
+
+
     // The scoped mixin saves the real tag name under data-tag-name
     let tagName = ((element.dataset && element.dataset.tagName) || element.tagName).toLowerCase();
     let namespace = i18n.options.fallbackNS;
     let overrideNamespace = getOverrideNamespace(namespace);
     let hasOverrides = false;
+    console.log(element.langDir);
     for (let lng of i18n.languages) {
-        overrides[lng] = await overrides[lng];
+        cacheOverrides(element.langDir, lng);
+        translationCache[lng] = await translationCache[lng];
         i18n.removeResourceBundle(lng, overrideNamespace);
-        if (overrides[lng] === undefined || overrides[lng][tagName] === undefined) continue;
-        let resources = overrides[lng][tagName];
+        if (translationCache[lng] === undefined || translationCache[lng][tagName] === undefined) continue;
+        let resources = translationCache[lng][tagName];
         hasOverrides = true;
         i18n.addResourceBundle(lng, overrideNamespace, resources);
     }

packages/common/src/i18n.js

-import {createInstance as _createInstance, setOverridesByPromise} from '../i18next.js';
+import {createInstance as _createInstance, setOverridesByGlobalCache} from '../i18next.js';
 
 import de from './i18n/de/translation.json';
 import en from './i18n/en/translation.json';
@@ -11,4 +11,4 @@ export function createInstanceGivenResources(en, de) {
     return _createInstance({en: en, de: de}, 'de', 'en');
 }
 
-export {setOverridesByPromise};
+export {setOverridesByGlobalCache};

packages/common/src/translation.js

 import {css, html} from 'lit';
 import {unsafeHTML} from 'lit/directives/unsafe-html.js';
 import DBPLitElement from '../dbp-lit-element';
-import {createInstanceGivenResources, setOverridesByPromise} from './i18n.js';
-
-// global variable as cache for translations
-const translationCache = {};
-
-// fetches overrides for given language
-async function fetchOverridesByLanguage(overrides, lng) {
-  let result = await
-      fetch(overrides + lng +'/translation.json', {
-          headers: {'Content-Type': 'application/json'},
-      });
-  let json = await result.json();
-  return json;
-}
-
-// handles translation cache promises
-async function cacheOverrides(overridesFile, lng) {
-  // use global var as cache
-  if (translationCache[lng] === undefined) {
-    // get translation.json for each lang
-    let response = fetchOverridesByLanguage(overridesFile, lng);
-    translationCache[lng] = response;
-    return response;
-  } else {
-    return translationCache[lng];
-  }
-}
+import {createInstanceGivenResources, setOverridesByGlobalCache} from './i18n.js';
 
 export class Translation extends DBPLitElement {
     constructor() {
@@ -72,8 +46,7 @@ export class Translation extends DBPLitElement {
 
       if (this.langDir) {
         for(let lng of this._i18n.languages) {
-          cacheOverrides(this.langDir, lng);
-          setOverridesByPromise(this._i18n, this, translationCache);
+          setOverridesByGlobalCache(this._i18n, this);
         }
       }
     }