feat: check the navigator languages too

application/source/dom/locale.mjs

@@ -6,8 +6,8 @@
  */
 
 import {parseLocale} from "../i18n/locale.mjs";
-
 import {getDocument} from "./util.mjs";
+import {getGlobalObject} from "../types/global.mjs";
 
 export {getLocaleOfDocument}
 
@@ -47,5 +47,39 @@ function getLocaleOfDocument() {
         }
     }
     
+    let navigatorLanguage = getNavigatorLanguage();
+    if (navigatorLanguage) {
+        return parseLocale(navigatorLanguage);
+    }
+
     return parseLocale(DEFAULT_LANGUAGE);
 }
+
+/**
+ * @private
+ * @returns {string|undefined|*}
+ * @see https://developer.mozilla.org/en-US/docs/Web/API/Navigator/language
+ * @see https://developer.mozilla.org/en-US/docs/Web/API/Navigator/languages
+ */
+const getNavigatorLanguage = () => {
+    const navigator = getGlobalObject('navigator');
+    if (navigator === undefined) {
+        return undefined;
+    }
+
+    if (navigator.hasOwnProperty('language')) {
+        const language = navigator.language;
+        if (typeof language === 'string' && language.length > 0) {
+            return language;
+        }
+        
+    }
+
+    const languages = navigator?.languages;
+    if (Array.isArray(languages) && languages.length>0) {
+        return languages[0];
+    }
+    
+    return undefined;
+
+}

application/source/i18n/translations.mjs

@@ -142,13 +142,16 @@ class Translations extends Base {
     }
 
     /**
-     * This method can be used to transfer overlays from an object. The keys are transferred and the values are entered as text.
+     * This method can be used to transfer overlays from an object. The keys are transferred, and the values are entered 
+     * as text.
      * 
-     * The values can either be character strings or, in the case of texts with plural forms, objects. The plural forms must be stored as text via a standard key "zero", "one", "two", "few", "many" and "other".
+     * The values can either be character strings or, in the case of texts with plural forms, objects. The plural forms
+     * must be stored as text via a standard key "zero", "one", "two", "few", "many" and "other".
      * 
      * Additionally, the key default can be specified, which will be used if no other key fits.
      * 
-     * In some languages, like for example in german, there is no own more number at the value 0. In these languages the function applies additionally zero.
+     * In some languages, like for example in German, there is no own more number at the value 0. In these languages, 
+     * the function applies additionally zero.
      *
      * ```
      * translations.assignTranslations({

development/test/cases/dom/locale.mjs

@@ -2,6 +2,7 @@
 
 import {expect} from "chai"
 
+import {Locale} from "../../../../application/source/i18n/locale.mjs";
 import {getLocaleOfDocument} from "../../../../application/source/dom/locale.mjs";
 import {initJSDOM} from "../../util/jsdom.mjs";
 
@@ -33,9 +34,23 @@ describe('Attributes', function () {
                 expect(getLocaleOfDocument().toString()).to.be.equal(a);
             })
             
+            
+
         });
 
 
     });
     
+    
+    it('return language en', function () {
+        let html = document.getElementsByTagName('html');
+        let node = html.item(0);
+
+        node.removeAttribute('lang');
+        const locale = getLocaleOfDocument();
+        expect(locale).to.be.instanceOf(Locale);
+        expect(locale.localeString).to.be.equal('en-US');
+    })
+    
+
 })
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