Add localStorage utility functions (#18)

Resolves #13

Author: drebrez

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - added `dateIsValid`, `dateIsLastDayOfMonth` and `dateDifferenceInDays` utility functions
 - added `newGuid` function and `emptyGuid` constant
+- added `getLocalStorageItem`, `setLocalStorageItem` and `removeLocalStorageItem` utility functions
 
 ## [0.1.1] - 2023-08-04
 

jest.config.js

@@ -2,4 +2,6 @@
 module.exports = {
   preset: "ts-jest",
   testEnvironment: "node",
+  resetMocks: false,
+  setupFiles: ["jest-localstorage-mock"],
 };

package.json

@@ -68,6 +68,7 @@
     "eslint-plugin-jsdoc": "^46.4.4",
     "eslint-plugin-storybook": "^0.6.12",
     "jest": "^29.6.1",
+    "jest-localstorage-mock": "^2.4.26",
     "nodemon": "^2.0.22",
     "prettier": "^2.8.8",
     "release-it": "^16.1.2",

src/index.ts

@@ -1,2 +1,3 @@
-export * from "./lib/date";
-export * from "./lib/enum";
+export * from "./lib/date";
+export * from "./lib/enum";
+export * from "./lib/localStorage";

src/lib/localStorage.spec.ts

@@ -0,0 +1,47 @@
+import { getLocalStorageItem, setLocalStorageItem, removeLocalStorageItem } from "./localStorage";
+
+describe("localStorage tests", () => {
+  beforeEach(() => {
+    localStorage.clear();
+    jest.clearAllMocks();
+  });
+
+  test("getLocalStorageItem not existing", () => {
+    expect(getLocalStorageItem("test")).toBeUndefined();
+  });
+
+  test("getLocalStorageItem existing", () => {
+    const testData = { field1: "hello", field2: "world" };
+    localStorage.setItem("test", JSON.stringify({ data: testData }));
+    expect(getLocalStorageItem("test")).toEqual(testData);
+  });
+
+  test("getLocalStorageItem expired", () => {
+    const expirationDate = new Date(new Date().getTime() - 1);
+    localStorage.setItem("test", JSON.stringify({ data: true, expirationDate: expirationDate.toISOString() }));
+    expect(localStorage.length).toBe(1);
+    expect(getLocalStorageItem("test")).toBeUndefined();
+    expect(localStorage.length).toBe(0);
+  });
+
+  test("setLocalStorageItem without expiration", () => {
+    const testData = { field1: "hello", field2: "world" };
+    setLocalStorageItem("test", testData);
+    expect(localStorage.length).toBe(1);
+    expect(localStorage.getItem("test")).toBe(JSON.stringify({ data: testData }));
+  });
+
+  test("setLocalStorageItem with expiration", () => {
+    const expirationDate = new Date(2050, 1, 1, 16, 30, 45, 123);
+    setLocalStorageItem("test", true, expirationDate);
+    expect(localStorage.length).toBe(1);
+    expect(localStorage.getItem("test")).toBe(JSON.stringify({ data: true, expirationDate: expirationDate.toISOString() }));
+  });
+
+  test("removeLocalStorageItem", () => {
+    localStorage.setItem("test", JSON.stringify({ data: true }));
+    expect(localStorage.length).toBe(1);
+    removeLocalStorageItem("test");
+    expect(localStorage.length).toBe(0);
+  });
+});

src/lib/localStorage.ts

@@ -0,0 +1,71 @@
+import { dateIsValid } from "./date";
+
+/**
+ * The localStorage item
+ */
+interface LocalStorageItem<T> {
+  /**
+   * The data
+   */
+  data: T;
+
+  /**
+   * The expiration date
+   */
+  expirationDate?: Date;
+}
+
+/**
+ * Check if the localStorage is supported
+ */
+const checkLocalStorageSupport = () => {
+  if (typeof localStorage === "undefined") {
+    throw new Error("localStorage not supported");
+  }
+};
+
+/**
+ * Get an item from the localStorage
+ * @param key The key
+ * @returns The item
+ */
+export function getLocalStorageItem<T>(key: string): T | undefined {
+  checkLocalStorageSupport();
+
+  const item = localStorage.getItem(key);
+  if (!item) {
+    return undefined;
+  }
+
+  const parsedItem = JSON.parse(item) as LocalStorageItem<T>;
+
+  if (parsedItem.expirationDate) {
+    const revivedExpirationDate = new Date(parsedItem.expirationDate);
+    if (dateIsValid(revivedExpirationDate) && revivedExpirationDate < new Date()) {
+      localStorage.removeItem(key);
+      return undefined;
+    }
+  }
+
+  return parsedItem.data;
+}
+
+/**
+ * Set an item in the localStorage
+ * @param key The key
+ * @param data The item data
+ * @param expirationDate The expiration date
+ */
+export function setLocalStorageItem<T>(key: string, data: T, expirationDate?: Date): void {
+  checkLocalStorageSupport();
+  localStorage.setItem(key, JSON.stringify({ data, expirationDate }));
+}
+
+/**
+ * Remove an item from the localStorage
+ * @param key The key
+ */
+export function removeLocalStorageItem(key: string): void {
+  checkLocalStorageSupport();
+  localStorage.removeItem(key);
+}

yarn.lock

@@ -3993,6 +3993,11 @@ jest-leak-detector@^29.6.1:
     jest-get-type "^29.4.3"
     pretty-format "^29.6.1"
 
+jest-localstorage-mock@^2.4.26:
+  version "2.4.26"
+  resolved "https://registry.yarnpkg.com/jest-localstorage-mock/-/jest-localstorage-mock-2.4.26.tgz#7d57fb3555f2ed5b7ed16fd8423fd81f95e9e8db"
+  integrity sha512-owAJrYnjulVlMIXOYQIPRCCn3MmqI3GzgfZCXdD3/pmwrIvFMXcKVWZ+aMc44IzaASapg0Z4SEFxR+v5qxDA2w==
+
 jest-matcher-utils@^29.6.1:
   version "29.6.1"
   resolved "https://registry.yarnpkg.com/jest-matcher-utils/-/jest-matcher-utils-29.6.1.tgz#6c60075d84655d6300c5d5128f46531848160b53"