nodejs · ovflowd · Nov 17, 2022 · Nov 14, 2022 · Nov 14, 2022 · Nov 14, 2022
diff --git a/package-lock.json b/package-lock.json
diff --git a/src/hooks/__tests__/useFeatureToggles.test.tsx b/src/hooks/__tests__/useFeatureToggles.test.tsx
@@ -1,6 +1,7 @@
 import React from 'react';
 import { render } from '@testing-library/react';
 import { useFeatureToggles } from '../useFeatureToggles';
+import { appStorage } from '../useStorage';
 import { FeatureToggleProvider } from '../../providers';
 
 describe('useFeatureToggles', () => {
@@ -15,65 +16,57 @@ describe('useFeatureToggles', () => {
     );
   };
 
-  it('should contain feature flag', () => {
-    const localStorageGetSpy = jest
-      .fn()
-      .mockImplementation(() => '["feature-flag-mock"]');
+  const setItemMock = jest.fn();
+  const getItemMock = jest.fn();
+
+  beforeEach(() => {
+    Storage.prototype.setItem = setItemMock;
+    Storage.prototype.getItem = getItemMock;
 
-    Object.defineProperty(window, 'localStorage', {
-      writable: true,
-      value: {
-        getItem: localStorageGetSpy,
-      },
-    });
+    appStorage.clear();
+  });
+
+  afterEach(() => {
+    setItemMock.mockRestore();
+    getItemMock.mockRestore();
+  });
+
+  it('should contain feature flag', () => {
+    getItemMock.mockReturnValue('["feature-flag-mock"]');
 
     const { container } = render(
       <FeatureToggleProvider>
         <FeatureFlagRenderer />
       </FeatureToggleProvider>
     );
 
-    expect(localStorageGetSpy).toHaveBeenCalledWith('node_featureFlags');
+    expect(getItemMock).toHaveBeenCalledWith('node_featureFlags');
     expect(container).toMatchSnapshot();
   });
 
   it('should not contain feature flag', () => {
-    const localStorageGetSpy = jest.fn().mockImplementation(() => '[]');
-
-    Object.defineProperty(window, 'localStorage', {
-      writable: true,
-      value: {
-        getItem: localStorageGetSpy,
-      },
-    });
+    getItemMock.mockReturnValue('[]');
 
     const { container } = render(
       <FeatureToggleProvider>
         <FeatureFlagRenderer />
       </FeatureToggleProvider>
     );
 
-    expect(localStorageGetSpy).toHaveBeenCalledWith('node_featureFlags');
+    expect(getItemMock).toHaveBeenCalledWith('node_featureFlags');
     expect(container).toMatchSnapshot();
   });
 
   it('should work if localstorage item does not exist ', () => {
-    const localStorageGetSpy = jest.fn().mockImplementation(() => null);
-
-    Object.defineProperty(window, 'localStorage', {
-      writable: true,
-      value: {
-        getItem: localStorageGetSpy,
-      },
-    });
+    getItemMock.mockReturnValue(null);
 
     const { container } = render(
       <FeatureToggleProvider>
         <FeatureFlagRenderer />
       </FeatureToggleProvider>
     );
 
-    expect(localStorageGetSpy).toHaveBeenCalledWith('node_featureFlags');
+    expect(getItemMock).toHaveBeenCalledWith('node_featureFlags');
     expect(container).toMatchSnapshot();
   });
 });
diff --git a/src/hooks/useBrowserLanguageDetection.ts b/src/hooks/useBrowserLanguageDetection.ts
@@ -1,33 +1,30 @@
 import { useEffect } from 'react';
 import { useLocalization } from 'gatsby-theme-i18n';
+import { useStorage } from './useStorage';
 import { useNavigateToDifferentLocale } from './useNavigateToDifferentLocale';
 import { detectLanguage } from '../util/detectLanguage';
 
-const languageStorageKey = 'NODE_DEV_LAST_LANGUAGE';
-
-const lastLanguageStorage = {
-  getItem: () => window.localStorage.getItem(languageStorageKey),
-  setItem: (currentLocale: string) =>
-    window.localStorage.setItem(languageStorageKey, currentLocale),
-};
+const languageStorageKey = 'node_currentLocale';
 
 export const useBrowserLanguageDetection = () => {
   const { locale: currentLocale } = useLocalization();
   const { navigate } = useNavigateToDifferentLocale();
+  const { getItem, setItem } = useStorage();
 
   useEffect(() => {
-    if (lastLanguageStorage.getItem() === null) {
+    if (getItem(languageStorageKey) === undefined) {
       // Attempts to retrieve a Language that we suport that is accepted by the user
       // We use navigator.languages to identify the language preference of an user
       const matchingBrowserLanguage = detectLanguage();
 
       if (matchingBrowserLanguage) {
-        lastLanguageStorage.setItem(matchingBrowserLanguage);
+        setItem(languageStorageKey, matchingBrowserLanguage);
 
         navigate(matchingBrowserLanguage);
+        return;
       }
-    } else if (lastLanguageStorage.getItem() !== currentLocale) {
-      lastLanguageStorage.setItem(currentLocale);
     }
+
+    setItem(languageStorageKey, currentLocale);
   }, [currentLocale]);
 };
diff --git a/src/hooks/useStorage.ts b/src/hooks/useStorage.ts
@@ -0,0 +1,59 @@
+import { useEffect } from 'react';
+
+// Creates a permanent storage to be used between all the parts of the Application
+// So it doesn't matter where this hook gets created it will be global.
+// Note.: This could be moved within a Provider to move it to a React-isolated context-tree instead of a global runtime one.
+export const appStorage = new Map<string, string>();
+
+const syncWithBrowser = () => {
+  if (typeof localStorage === 'object') {
+    return {
+      sendToBrowser: (k: string, v: string) => localStorage.setItem(k, v),
+      getFromBrowser: (k: string) => localStorage.getItem(k) || undefined,
+    };
+  }
+
+  return {
+    sendToBrowser: () => undefined,
+    getFromBrowser: () => undefined,
+  };
+};
+
+export const useStorage = () => {
+  const { sendToBrowser, getFromBrowser } = syncWithBrowser();
+
+  const setItem = (key: string, value: unknown) =>
+    appStorage.set(key, JSON.stringify(value));
+
+  const getItem = (key: string) => {
+    // Attempts to retrieve items from the App Storage, but if they don't exist yet
+    // They might exist in the Browser Local Storage. This is useful as we retrieve things
+    // From the Web Storage API only if they don't exist in the App Storage
+    const storageItem = appStorage.get(key) || getFromBrowser(key);
+    const parsedValue = storageItem ? JSON.parse(storageItem) : undefined;
+
+    // If a said item doesn't exist in the App Storage we will create one
+    // On the App Storage that will either be the value from the Web Storage if it exists
+    // Or `undefined`. This is an interesting approach as it will ensure that all requested keys
+    // at one point will exist in the Web Storage, and keeps things in sync.
+    if (!appStorage.has(key)) {
+      setItem(key, parsedValue);
+    }
+
+    return parsedValue;
+  };
+
+  const flushToStorage = () =>
+    [...appStorage.entries()].forEach(([k, v]) => sendToBrowser(k, v));
+
+  useEffect(() => {
+    // Instead of flushing to the localStorage on every change, we flush once the Application
+    // is being unloaded, so it allows us to update all changes at once instead of constantly
+    // invoking the Web Storage APIs for every change we need, as the "authoritative storage" is the app itself
+    window.addEventListener('unload', flushToStorage);
+
+    return () => window.removeEventListener('unload', flushToStorage);
+  }, []);
+
+  return { getItem, setItem };
+};
diff --git a/src/layouts/default.tsx b/src/layouts/default.tsx
@@ -5,6 +5,7 @@ import { CommonComponents } from '../components';
 import Header from '../sections/Header';
 import Footer from '../sections/Footer';
 import { FeatureToggleProvider } from '../providers';
+import { useBrowserLanguageDetection } from '../hooks/useBrowserLanguageDetection';
 
 interface Props {
   title?: string;
@@ -35,20 +36,28 @@ const Layout = ({
   img,
   showFooter = true,
   showRandomContributor = false,
-}: React.PropsWithChildren<Props>): JSX.Element => (
-  <FeatureToggleProvider>
-    <ThemeProvider theme={defaultTheme}>
-      <CommonComponents.SEO title={title} description={description} img={img} />
-      <MotionConfig reducedMotion="user">
-        <div className="layout-container">
-          <Header />
-          {children}
-          {showRandomContributor && <CommonComponents.RandomContributor />}
-          {showFooter && <Footer />}
-        </div>
-      </MotionConfig>
-    </ThemeProvider>
-  </FeatureToggleProvider>
-);
+}: React.PropsWithChildren<Props>): JSX.Element => {
+  useBrowserLanguageDetection();
+
+  return (
+    <FeatureToggleProvider>
+      <ThemeProvider theme={defaultTheme}>
+        <CommonComponents.SEO
+          title={title}
+          description={description}
+          img={img}
+        />
+        <MotionConfig reducedMotion="user">
+          <div className="layout-container">
+            <Header />
+            {children}
+            {showRandomContributor && <CommonComponents.RandomContributor />}
+            {showFooter && <Footer />}
+          </div>
+        </MotionConfig>
+      </ThemeProvider>
+    </FeatureToggleProvider>
+  );
+};
 
 export default Layout;
diff --git a/src/providers/FeatureToggles/index.tsx b/src/providers/FeatureToggles/index.tsx
@@ -1,4 +1,5 @@
 import React, { createContext, useMemo } from 'react';
+import { useStorage } from '../../hooks/useStorage';
 
 type Props = { children?: React.ReactNode };
 
@@ -7,26 +8,20 @@ const FEATURE_FLAGS_STORAGE = 'node_featureFlags';
 export const FeatureToggleContext = createContext<string[]>([]);
 
 export const FeatureToggleProvider: React.FC<Props> = ({ children }) => {
+  const { getItem } = useStorage();
+
   const featureFlags = useMemo(() => {
-    try {
-      const storageItem = localStorage.getItem(FEATURE_FLAGS_STORAGE) || '[]';
-
-      const parsedItem = JSON.parse(storageItem);
-
-      // We want to guarantee the parsedItem is truthy and and Array
-      if (parsedItem && Array.isArray(parsedItem)) {
-        // Lastly we filter non-string objects as we want to avoid code injection such as XSS
-        // from starting from our feature flags
-        return [...parsedItem].filter(f => typeof f === 'string' && f.length);
-      }
-
-      return [];
-    } catch (__noop) {
-      // We don't care if the JSON.parse or localStorage.getItem fail
-      // as we will just disable the feature flags then
-      return [];
+    const parsedItem = getItem(FEATURE_FLAGS_STORAGE) || [];
+
+    // We want to guarantee the parsedItem is truthy and and Array
+    if (parsedItem && Array.isArray(parsedItem)) {
+      // Lastly we filter non-string objects as we want to avoid code injection such as XSS
+      // from starting from our feature flags
+      return [...parsedItem].filter(f => typeof f === 'string' && f.length);
     }
-  }, []);
+
+    return [];
+  }, [getItem]);
 
   return (
     <FeatureToggleContext.Provider value={featureFlags}>