fix: add defaultNS as an optional ns value

Author: felixmosh

__tests__/client-hmr.spec.js

@@ -266,6 +266,26 @@ describe('client-hmr', () => {
     expect(i18nMock.changeLanguage).toHaveBeenCalledWith('en-US');
   });
 
+  it('should support defaultNS as optional ns', async () => {
+    i18nMock.options = {
+      backend: {},
+      ns: [],
+      defaultNS: ['common'],
+    };
+    i18nMock.language = 'en-US';
+
+    applyClientHMR(i18nMock);
+
+    await whenHotTriggeredWith(['common/en-US']);
+
+    expect(i18nMock.reloadResources).toHaveBeenCalledWith(
+      ['en-US'],
+      ['common'],
+      expect.any(Function)
+    );
+    expect(i18nMock.changeLanguage).toHaveBeenCalledWith('en-US');
+  });
+
   it('should support complex localePath {{ns}}/locales/{{lng}}.json', async () => {
     i18nMock.options = { backend: {}, ns: ['nested/name-space'] };
     i18nMock.language = 'en-US';

__tests__/server-hmr.spec.js

@@ -139,6 +139,19 @@ describe('server-hmr', () => {
       );
     });
 
+    it('should support defaultNS as source of ns', async () => {
+      const update = { lang: 'en', ns: 'nested/fallback-name-space' };
+      i18nMock.options.ns = [];
+      i18nMock.options.defaultNS = update.ns;
+      whenNativeHMRTriggeredWith([`${update.lang}/${update.ns}`]);
+
+      expect(i18nMock.reloadResources).toHaveBeenCalledWith(
+        [update.lang],
+        [update.ns],
+        expect.any(Function)
+      );
+    });
+
     it('should notify on successful change', async () => {
       jest.spyOn(global.console, 'log');
 
@@ -293,6 +306,19 @@ describe('server-hmr', () => {
       );
     });
 
+    it('should support defaultNS as source of ns', async () => {
+      const update = { lang: 'en', ns: 'nested/fallback-name-space' };
+      i18nMock.options.ns = [];
+      i18nMock.options.defaultNS = update.ns;
+      plugin.callbacks[0]({ changedFiles: [`${update.lang}/${update.ns}`] });
+
+      expect(i18nMock.reloadResources).toHaveBeenCalledWith(
+        [update.lang],
+        [update.ns],
+        expect.any(Function)
+      );
+    });
+
     it('should ignore changes of none loaded namespace', async () => {
       jest.spyOn(global.console, 'log');
       i18nMock.options = { backend: {}, ns: ['name-space'] };

lib/utils.js

@@ -31,7 +31,13 @@ function printList(list) {
 
 function extractList(changedFiles, i18nInstance) {
   const namespaces = uniqueList(
-    [].concat(i18nInstance.options.ns, i18nInstance.options.fallbackNS || []).filter(Boolean)
+    []
+      .concat(
+        i18nInstance.options.ns,
+        i18nInstance.options.fallbackNS,
+        i18nInstance.options.defaultNS
+      )
+      .filter(Boolean)
   );
   const languages = uniqueList(
     [].concat(