getBrowserLanguage

1/**
2 * Returns the browser's preferred language (e.g., "en", "en-US", "ru").
3 *
4 * @param fallback - A fallback value if language is unavailable.
5 * @returns The language string or the fallback.
6 */
7export function getBrowserLanguage(fallback = 'en'): string {
8  if (typeof navigator === 'undefined') return fallback;
9
10  return navigator.language || fallback;
11}

1test('getBrowserLanguage - returns navigator.language if available', () => {
2  const original = navigator.language;
3  Object.defineProperty(navigator, 'language', {
4    configurable: true,
5    get: () => 'fr-CA',
6  });
7
8  expect(getBrowserLanguage()).toBe('fr-CA');
9
10  Object.defineProperty(navigator, 'language', {
11    configurable: true,
12    get: () => original,
13  });
14});
15
16test('getBrowserLanguage - returns fallback if navigator is undefined', () => {
17  const original = global.navigator;
18  // @ts-ignore
19  delete global.navigator;
20
21  expect(getBrowserLanguage('ru')).toBe('ru');
22
23  global.navigator = original;
24});