isMac: migrate to typescript and add test

Author: clairep94

.eslintrc

@@ -30,6 +30,7 @@
       }
     ],
     "react/jsx-filename-extension": [1, { "extensions": [".jsx", ".tsx"] }],
+    "import/prefer-default-export": "off",
     "comma-dangle": 0,  // not sure why airbnb turned this on. gross!
     "default-param-last": 0,
     "no-else-return" :0,

client/utils/device.js

@@ -0,0 +1,45 @@
+import { isMac } from './device';
+
+describe('isMac', () => {
+  const originalUserAgent = navigator.userAgent;
+
+  afterEach(() => {
+    // Restore the original userAgent after each test
+    Object.defineProperty(navigator, 'userAgent', {
+      value: originalUserAgent,
+      configurable: true
+    });
+  });
+
+  it('returns true when userAgent contains "Mac"', () => {
+    Object.defineProperty(navigator, 'userAgent', {
+      value: 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7)',
+      configurable: true
+    });
+    expect(isMac()).toBe(true);
+  });
+
+  it('returns false when userAgent does not contain "Mac"', () => {
+    Object.defineProperty(navigator, 'userAgent', {
+      value: 'Mozilla/5.0 (Windows NT 10.0; Win64; x64)',
+      configurable: true
+    });
+    expect(isMac()).toBe(false);
+  });
+
+  it('returns false when navigator agent is null', () => {
+    Object.defineProperty(navigator, 'userAgent', {
+      value: null,
+      configurable: true
+    });
+    expect(isMac()).toBe(false);
+  });
+
+  it('returns false when navigator agent is undefined', () => {
+    Object.defineProperty(navigator, 'userAgent', {
+      value: undefined,
+      configurable: true
+    });
+    expect(isMac()).toBe(false);
+  });
+});

client/utils/device.test.ts

@@ -0,0 +1,10 @@
+/**
+ * Checks if the user's OS is macOS based on the user agent string.
+ * This is the preferred method over navigator.platform, which is now deprecated:
+ *   - see https://developer.mozilla.org/en-US/docs/Web/API/Navigator/platform
+ */
+export function isMac(): boolean {
+  return typeof navigator?.userAgent === 'string'
+    ? navigator.userAgent.toLowerCase().includes('mac')
+    : false;
+}