fix: Issue when calling the loadLanguageAsync in parallel.

src/index.ts

@@ -132,7 +132,7 @@ export class I18n {
   /**
    * Stores the loaded languages.
    */
-  private static loaded: LanguageInterface[] = []
+  public static loaded: LanguageInterface[] = []
 
   // Stores options for the current instance
   private options: OptionsInterface
@@ -317,7 +317,7 @@ export class I18n {
     }
 
     const data: LanguageInterface = { lang, messages }
-    I18n.loaded.push(data)
+    this.addLoadedLang(data)
 
     return this.setLanguage(data)
   }
@@ -327,12 +327,27 @@ export class I18n {
       this.fallbackMessages[key] = value
     }
 
-    I18n.loaded.push({
+    this.addLoadedLang({
       lang: this.options.fallbackLang,
       messages
     })
   }
 
+  /**
+   * Adds to the array of loaded languages.
+   */
+  addLoadedLang(data: LanguageInterface): void {
+    const foundIndex = I18n.loaded.findIndex((item) => item.lang === data.lang)
+
+    if (foundIndex !== -1) {
+      I18n.loaded[foundIndex] = data
+
+      return
+    }
+
+    I18n.loaded.push(data)
+  }
+
   /**
    * Sets the language messages to the activeMessages.
    */

test/translate.test.ts

@@ -1,5 +1,5 @@
 import { mount } from '@vue/test-utils'
-import { i18nVue, trans, trans_choice, loadLanguageAsync, reset, getActiveLanguage, isLoaded, wTrans } from '../src'
+import { i18nVue, trans, trans_choice, loadLanguageAsync, reset, getActiveLanguage, isLoaded, wTrans, I18n } from '../src'
 import { reset as resetLoader } from '../src/loader'
 
 beforeEach(() => reset());
@@ -109,6 +109,21 @@ it('loads a lang', async () => {
   expect(wrapper.html()).toBe('<h1>Bem-vindo, Francisco!</h1>')
 })
 
+it('only keep one item for each lang even with multiple calls of the `loadLanguageAsync`', async () => {
+  const wrapper = await global.mountPlugin();
+
+  expect(I18n.loaded.length).toBe(1);
+
+  // Purpose call multiple times to replicate a multiple call.
+  await Promise.all([
+    loadLanguageAsync('en'),
+    loadLanguageAsync('en'),
+  ]);
+
+  expect(I18n.loaded.length).toBe(2);
+
+})
+
 it('returns the active lang', async () => {
   await global.mountPlugin();