feat: Add support for localStorage for the browser platform.

packages/sdk/browser/__tests__/platform/LocalStorage.test.ts

@@ -0,0 +1,139 @@
+import LocalStorage from '../../src/platform/LocalStorage';
+
+it('can set values', async () => {
+  const logger = {
+    debug: jest.fn(),
+    info: jest.fn(),
+    warn: jest.fn(),
+    error: jest.fn(),
+  };
+  // Storage here needs to be the global browser 'Storage' not the interface
+  // for our platform.
+  const spy = jest.spyOn(Storage.prototype, 'setItem');
+
+  const storage = new LocalStorage(logger);
+  storage.set('test-key', 'test-value');
+  expect(spy).toHaveBeenCalledWith('test-key', 'test-value');
+
+  expect(logger.debug).not.toHaveBeenCalled();
+  expect(logger.info).not.toHaveBeenCalled();
+  expect(logger.warn).not.toHaveBeenCalled();
+  expect(logger.error).not.toHaveBeenCalled();
+});
+
+it('can handle an error setting a value', async () => {
+  const logger = {
+    debug: jest.fn(),
+    info: jest.fn(),
+    warn: jest.fn(),
+    error: jest.fn(),
+  };
+  // Storage here needs to be the global browser 'Storage' not the interface
+  // for our platform.
+  const spy = jest.spyOn(Storage.prototype, 'setItem');
+  spy.mockImplementation(() => {
+    throw new Error('bad');
+  });
+
+  const storage = new LocalStorage(logger);
+  storage.set('test-key', 'test-value');
+
+  expect(logger.debug).not.toHaveBeenCalled();
+  expect(logger.info).not.toHaveBeenCalled();
+  expect(logger.warn).not.toHaveBeenCalled();
+  expect(logger.error).toHaveBeenCalledWith(
+    'Error setting key in localStorage: test-key, reason: Error: bad',
+  );
+});
+
+it('can get values', async () => {
+  const logger = {
+    debug: jest.fn(),
+    info: jest.fn(),
+    warn: jest.fn(),
+    error: jest.fn(),
+  };
+  // Storage here needs to be the global browser 'Storage' not the interface
+  // for our platform.
+  const spy = jest.spyOn(Storage.prototype, 'getItem');
+
+  const storage = new LocalStorage(logger);
+  storage.get('test-key');
+  expect(spy).toHaveBeenCalledWith('test-key');
+
+  expect(logger.debug).not.toHaveBeenCalled();
+  expect(logger.info).not.toHaveBeenCalled();
+  expect(logger.warn).not.toHaveBeenCalled();
+  expect(logger.error).not.toHaveBeenCalled();
+});
+
+it('can handle an error getting a value', async () => {
+  const logger = {
+    debug: jest.fn(),
+    info: jest.fn(),
+    warn: jest.fn(),
+    error: jest.fn(),
+  };
+  // Storage here needs to be the global browser 'Storage' not the interface
+  // for our platform.
+  const spy = jest.spyOn(Storage.prototype, 'getItem');
+  spy.mockImplementation(() => {
+    throw new Error('bad');
+  });
+
+  const storage = new LocalStorage(logger);
+  storage.get('test-key');
+
+  expect(logger.debug).not.toHaveBeenCalled();
+  expect(logger.info).not.toHaveBeenCalled();
+  expect(logger.warn).not.toHaveBeenCalled();
+  expect(logger.error).toHaveBeenCalledWith(
+    'Error getting key from localStorage: test-key, reason: Error: bad',
+  );
+});
+
+it('can clear values', async () => {
+  const logger = {
+    debug: jest.fn(),
+    info: jest.fn(),
+    warn: jest.fn(),
+    error: jest.fn(),
+  };
+  // Storage here needs to be the global browser 'Storage' not the interface
+  // for our platform.
+  const spy = jest.spyOn(Storage.prototype, 'removeItem');
+
+  const storage = new LocalStorage(logger);
+  storage.clear('test-key');
+  expect(spy).toHaveBeenCalledWith('test-key');
+
+  expect(logger.debug).not.toHaveBeenCalled();
+  expect(logger.info).not.toHaveBeenCalled();
+  expect(logger.warn).not.toHaveBeenCalled();
+  expect(logger.error).not.toHaveBeenCalled();
+});
+
+it('can handle an error clearing a value', async () => {
+  const logger = {
+    debug: jest.fn(),
+    info: jest.fn(),
+    warn: jest.fn(),
+    error: jest.fn(),
+  };
+  // Storage here needs to be the global browser 'Storage' not the interface
+  // for our platform.
+  const spy = jest.spyOn(Storage.prototype, 'removeItem');
+  spy.mockImplementation(() => {
+    throw new Error('bad');
+  });
+
+  const storage = new LocalStorage(logger);
+  storage.clear('test-key');
+
+  expect(logger.debug).not.toHaveBeenCalled();
+  expect(logger.info).not.toHaveBeenCalled();
+  expect(logger.warn).not.toHaveBeenCalled();
+  expect(logger.error).toHaveBeenCalledWith(
+    'Error clearing key from localStorage: test-key, reason: Error: bad',
+  );
+});

packages/sdk/browser/jest.config.js

@@ -0,0 +1,12 @@
+
+export default {
+  preset: 'ts-jest',
+  testEnvironment: 'jest-environment-jsdom',
+  transform: {
+      "^.+\\.tsx?$": "ts-jest"
+  // process `*.tsx` files with `ts-jest`
+  },
+  moduleNameMapper: {
+      '\\.(gif|ttf|eot|svg|png)$': '<rootDir>/test/__ mocks __/fileMock.js',
+  },
+}

packages/sdk/browser/package.json

@@ -39,7 +39,6 @@
   },
   "devDependencies": {
     "@launchdarkly/private-js-mocks": "0.0.1",
-    "@testing-library/react": "^14.1.2",
     "@trivago/prettier-plugin-sort-imports": "^4.1.1",
     "@types/jest": "^29.5.11",
     "@typescript-eslint/eslint-plugin": "^6.20.0",
@@ -52,9 +51,11 @@
     "eslint-plugin-jest": "^27.6.3",
     "eslint-plugin-prettier": "^5.0.0",
     "jest": "^29.7.0",
+    "jest-environment-jsdom": "^29.7.0",
     "prettier": "^3.0.0",
     "rimraf": "^5.0.5",
     "ts-jest": "^29.1.1",
+    "ts-node": "^10.9.2",
     "typedoc": "0.25.0",
     "typescript": "^5.5.3",
     "vite": "^5.4.1",

packages/sdk/browser/src/platform/BrowserPlatform.ts

@@ -0,0 +1,22 @@
+import {
+  LDOptions,
+  Storage,
+  /* platform */
+} from '@launchdarkly/js-client-sdk-common';
+
+import LocalStorage, { isLocalStorageSupported } from './LocalStorage';
+
+export default class BrowserPlatform /* implements platform.Platform */ {
+  // encoding?: Encoding;
+  // info: Info;
+  // fileSystem?: Filesystem;
+  // crypto: Crypto;
+  // requests: Requests;
+  storage?: Storage;
+
+  constructor(options: LDOptions) {
+    if (isLocalStorageSupported()) {
+      this.storage = new LocalStorage(options.logger);
+    }
+  }
+}

packages/sdk/browser/src/platform/LocalStorage.ts

@@ -0,0 +1,42 @@
+import type { LDLogger, Storage } from '@launchdarkly/js-client-sdk-common';
+
+export function isLocalStorageSupported() {
+  // Checking a symbol using typeof is safe, but directly accessing a symbol
+  // which is not defined would be an error.
+  return typeof localStorage !== 'undefined';
+}
+
+/**
+ * Implementation of Storage using localStorage for the browser.
+ *
+ * The Storage API is async, and localStorage is synchronous. This is fine,
+ * and none of the methods need to internally await their operations.
+ */
+export default class PlatformStorage implements Storage {
+  constructor(private readonly logger?: LDLogger) {}
+  async clear(key: string): Promise<void> {
+    try {
+      localStorage.removeItem(key);
+    } catch (error) {
+      this.logger?.error(`Error clearing key from localStorage: ${key}, reason: ${error}`);
+    }
+  }
+
+  async get(key: string): Promise<string | null> {
+    try {
+      const value = localStorage.getItem(key);
+      return value ?? null;
+    } catch (error) {
+      this.logger?.error(`Error getting key from localStorage: ${key}, reason: ${error}`);
+      return null;
+    }
+  }
+
+  async set(key: string, value: string): Promise<void> {
+    try {
+      localStorage.setItem(key, value);
+    } catch (error) {
+      this.logger?.error(`Error setting key in localStorage: ${key}, reason: ${error}`);
+    }
+  }
+}