fix(isLanguageAvailable): do not return regionless-locales in older browsers with languageOnly set to false

wopian · wopian · commit fa46526755ed · 2020-07-15T00:54:28.000+01:00
diff --git a/packages/preferred-locale/src/index.spec.browser.js b/packages/preferred-locale/src/index.spec.browser.js
@@ -0,0 +1,17 @@
+import preferredLocale from './'
+import * as isLocaleSupported from './utils/isLocaleSupported'
+
+describe('preferredLocale', () => {
+  describe('without Intl.Locale supported', () => {
+    beforeEach(() => {
+      jest.spyOn(isLocaleSupported, 'isLocaleSupported').mockReturnValue(false)
+    })
+
+    it('handles region-less locales', () => {
+      expect.assertions(1)
+      jest.spyOn(navigator, 'languages', 'get').mockReturnValue([ 'en', 'en-US' ])
+      const translations = [ 'fr-FR', 'id-ID', 'en-US' ]
+      expect(preferredLocale(translations, 'en-US')).toBe('en-US')
+    })
+  })
+})
diff --git a/packages/preferred-locale/src/utils/availableLocales/index.js b/packages/preferred-locale/src/utils/availableLocales/index.js
@@ -6,6 +6,7 @@ import { isLanguageAvailable } from '../'
  * @param {string[]} translatedLocales Translations provided by the application
  * @param {Object} [options={}] Configuration options
  * @param {boolean} [options.regionLowerCase=false] If true, returns `en-us` instead of `en-US`
+ * @param {boolean} [options.languageOnly=false] If true, returns `en` instead of `en-US` or `en-us`
  * @returns {Object[]} Locales supported by both the browser and application
  * @private
  */
@@ -15,6 +16,7 @@ export const availableLocales = (
   options = {}
 ) => {
   if (!options.regionLowerCase) options.regionLowerCase = false
+  if (!options.languageOnly) options.languageOnly = false
 
   return userLocales.filter((userLocale, index, array) => {
     const formattedLocale = options.regionLowerCase
@@ -29,7 +31,8 @@ export const availableLocales = (
       formattedLocale,
       translatedLocales,
       index,
-      array
+      array,
+      options
     )
   })
 }
diff --git a/packages/preferred-locale/src/utils/isLanguageAvailable/index.js b/packages/preferred-locale/src/utils/isLanguageAvailable/index.js
@@ -6,28 +6,39 @@ import { isLocaleSupported } from '../'
  * @param {string[]} translatedLocales Translations provided by the application
  * @param {number} index The index of the unified browser locale in `array`
  * @param {Object[]} array The unified browser locale array
+ * @param {Object} [options={}] Configuration options
+ * @param {boolean} [options.languageOnly=false] If true, returns `en` instead of `en-US` or `en-us`
  * @returns {boolean} Is the language available?
  * @private
  */
 export const isLanguageAvailable = (
   userLocale,
   translatedLocales,
   index,
-  array
-) => translatedLocales.filter(translatedLocale => {
-  // Strip the region code from both locales (en-gb -> en)
-  const translatedLanguage = isLocaleSupported()
-    ? new Intl.Locale(translatedLocale).minimize().language
-    : translatedLocale.split('-')[0]
-  const browserLanguage = isLocaleSupported()
-    ? new Intl.Locale(userLocale).minimize().language
-    : userLocale.split('-')[0]
+  array,
+  options = {}
+) => {
+  if (!options.languageOnly) options.languageOnly = false
 
-  const isLanguageAvailable = translatedLanguage === browserLanguage
+  return translatedLocales.filter(translatedLocale => {
+    const localeSupported = isLocaleSupported()
+    // Backwards compatibility for older browsers
+    if (!localeSupported && !options.languageOnly && userLocale.split('-')[1] === undefined) return false
 
-  // Update the locale field to the canonical region if there is no translations for the browser-provided region
-  // For example, en-XX (unknown region) to en-US (translated)
-  if (isLanguageAvailable) array[index].locale = translatedLanguage
+    // Strip the region code from both locales (en-gb -> en)
+    const translatedLanguage = localeSupported
+      ? new Intl.Locale(translatedLocale).minimize().language
+      : translatedLocale.split('-')[0]
+    const browserLanguage = localeSupported
+      ? new Intl.Locale(userLocale).minimize().language
+      : userLocale.split('-')[0]
 
-  return isLanguageAvailable
-}).length > 0
+    const isLanguageAvailable = translatedLanguage === browserLanguage
+
+    // Update the locale field to the canonical region if there is no translations for the browser-provided region
+    // For example, en-XX (unknown region) to en-US (translated)
+    if (isLanguageAvailable) array[index].locale = translatedLanguage
+
+    return isLanguageAvailable
+  }).length > 0
+}
