storage.ts

/**
 * Checks if the specified Web Storage API exists and is accessible
 * @param storage - Web Storage API
 * @returns true, if the Web Storage API is accessible
 */
const isStorageEnabled = (storage?: Storage): storage is Storage => {
  if (!storage) return false;
  try {
    const key = `__storage__test`;
    storage.setItem(key, '');
    storage.removeItem(key);
    return true;
  } catch {
    return false;
  }
};

/**
 * Utilizes a `Map` cache backed Web Storage API when the specified Web Storage API isn't accessible
 * @param storage - possible Web Storage API
 * @returns a Web Storage API implementation
 */
const createStorage = (storage?: Storage): Storage => {
  if (isStorageEnabled(storage)) {
    return storage;
  }

  const storageFallbackCache = new Map<string, string>();

  return {
    clear(): void {
      storageFallbackCache.clear();
    },
    getItem(key: string): string | null {
      // eslint-disable-next-line unicorn/no-null
      return storageFallbackCache.get(key) ?? null;
    },
    key(index: number): string | null {
      // eslint-disable-next-line unicorn/no-null
      return [...storageFallbackCache.values()][index] ?? null;
    },
    get length() {
      return storageFallbackCache.size;
    },
    removeItem(key: string): void {
      storageFallbackCache.delete(key);
    },
    setItem(key: string, value: string): void {
      storageFallbackCache.set(key, value);
    },
  };
};

// eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
export const localStorage = createStorage(window?.localStorage);

// eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
export const sessionStorage = createStorage(window?.sessionStorage);