scaleway · philibea · May 19, 2021 · May 17, 2021
diff --git a/packages/use-i18n/README.md b/packages/use-i18n/README.md
@@ -30,8 +30,9 @@ Use of local `variables` and `namespace` to dynamically load locales.
 your loaders will be:
 
 ```js
-const load = ({ locale, namespace }) => import(`./locales/${locale}/${namespace}`)
-const loadDateLocale = (locale) => import(`date-fns/locale/${locale}/index`)
+const load = ({ locale, namespace }) =>
+  import(`./locales/${locale}/${namespace}`)
+const loadDateLocale = locale => import(`date-fns/locale/${locale}/index`)
 ```
 
 Inside your app you will need to use useTranslation to load namespace locales.
@@ -102,23 +103,16 @@ const App = () => {
 }
 ```
 
+In a case you will need to avoid somes useless re-render. you can wait that all your namespaces are loaded
+
 ```js
-import { useI18n } from '@scaleway/use-i18n'
+import { useTranslation } from '@scaleway/use-i18n'
 
 const App = () => {
-  const i18n = useTranslation()
-  const { loadTranslations } = i18n
   const namespaces = ['app', 'common']
+  const { t, isLoaded } = useTranslation(namespaces)
 
-  const key = namespaces.join(',')
-
-  useEffect(
-    () =>
-      key.split(',').map(async namespace => loadTranslations(namespace, load)),
-    [loadTranslations, key, load],
-  )
-
-  return <>{i18n.t('app.user')}(</>
+  return isLoaded ? <>{t('app.user')}(</> : null
 }
 ```
 

diff --git a/packages/use-i18n/package.json b/packages/use-i18n/package.json
@@ -34,11 +34,13 @@
   },
   "peerDependencies": {
     "date-fns": "2.x",
-    "react": "17.x"
+    "react": "17.x",
+    "react-dom": "17.x"
   },
   "devDependencies": {
     "@testing-library/react-hooks": "^6.0.0",
     "mockdate": "^3.0.5",
-    "react": "17.0.2"
+    "react": "17.0.2",
+    "react-dom": "17.0.2"
   }
 }
diff --git a/packages/use-i18n/src/__tests__/index.js b/packages/use-i18n/src/__tests__/index.js
@@ -157,8 +157,14 @@ describe('i18n hook', () => {
         }),
       },
     )
+
+    // current local will be 'en' based on navigator
     // await load of locales
+    act(() => {
+      result.current.switchLocale('fr')
+    })
     await waitForNextUpdate()
+
     expect(result.current.translations).toStrictEqual({
       en: {
         'user.languages': 'Languages',
@@ -170,10 +176,6 @@ describe('i18n hook', () => {
         'user.name': 'Prénom',
       },
     })
-    act(() => {
-      result.current.switchLocale('fr')
-    })
-    await waitForNextUpdate()
 
     expect(result.current.t('user.languages')).toEqual('')
     expect(result.current.t('user.lastName')).toEqual('Nom')

diff --git a/packages/use-i18n/src/index.js b/packages/use-i18n/src/index.js
@@ -10,6 +10,7 @@ import React, {
   useMemo,
   useState,
 } from 'react'
+import ReactDOM from 'react-dom'
 import 'intl-pluralrules'
 
 const LOCALE_ITEM_STORAGE = 'locale'
@@ -21,6 +22,27 @@ const prefixKeys = prefix => obj =>
     return acc
   }, {})
 
+const areNamespacesLoaded = (namespaces, loadedNamespaces) =>
+  namespaces.every(n => loadedNamespaces.includes(n))
+
+const getLocaleFallback = locale => locale.split('-')[0].split('_')[0]
+
+const getCurrentLocale = ({
+  defaultLocale,
+  supportedLocales,
+  localeItemStorage,
+}) => {
+  const languages = navigator.languages || [navigator.language]
+  const browserLocales = [...new Set(languages.map(getLocaleFallback))]
+  const localeStorage = localStorage.getItem(localeItemStorage)
+
+  return (
+    localeStorage ||
+    browserLocales.find(locale => supportedLocales.includes(locale)) ||
+    defaultLocale
+  )
+}
+
 const I18nContext = createContext()
 
 export const useI18n = () => {
@@ -37,16 +59,19 @@ export const useTranslation = (namespaces = [], load) => {
   if (context === undefined) {
     throw new Error('useTranslation must be used within a I18nProvider')
   }
-  const { loadTranslations } = context
+  const { loadTranslations, namespaces: loadedNamespaces } = context
 
   const key = namespaces.join(',')
-  useEffect(
-    () =>
-      key.split(',').map(async namespace => loadTranslations(namespace, load)),
-    [loadTranslations, key, load],
+  useEffect(() => {
+    key.split(',').map(async namespace => loadTranslations(namespace, load))
+  }, [loadTranslations, key, load])
+
+  const isLoaded = useMemo(
+    () => areNamespacesLoaded(namespaces, loadedNamespaces),
+    [loadedNamespaces, namespaces],
   )
 
-  return context
+  return { ...context, isLoaded }
 }
 
 // https://formatjs.io/docs/intl-messageformat/
@@ -66,27 +91,18 @@ const I18nContextProvider = ({
   localeItemStorage,
   supportedLocales,
 }) => {
-  const [currentLocale, setCurrentLocale] = useState(defaultLocale)
-  const [locales, setLocales] = useState(supportedLocales)
+  const [currentLocale, setCurrentLocale] = useState(
+    getCurrentLocale({ defaultLocale, localeItemStorage, supportedLocales }),
+  )
   const [translations, setTranslations] = useState(defaultTranslations)
+  const [namespaces, setNamespaces] = useState([])
   const [dateFnsLocale, setDateFnsLocale] = useState()
 
-  const getLocaleFallback = useCallback(
-    locale => locale.split('-')[0].split('_')[0],
-    [],
-  )
-
-  const getCurrentLocale = useCallback(() => {
-    const languages = navigator.languages || [navigator.language]
-    const browserLocales = [...new Set(languages.map(getLocaleFallback))]
-    const localeStorage = localStorage.getItem(localeItemStorage)
-
-    return (
-      localeStorage ||
-      browserLocales.find(locale => locales.includes(locale)) ||
-      defaultLocale
-    )
-  }, [defaultLocale, getLocaleFallback, locales, localeItemStorage])
+  useEffect(() => {
+    loadDateLocale(currentLocale === 'en' ? 'en-GB' : currentLocale)
+      .then(setDateFnsLocale)
+      .catch(() => loadDateLocale('en-GB').then(setDateFnsLocale))
+  }, [loadDateLocale, currentLocale])
 
   const loadTranslations = useCallback(
     async (namespace, load = defaultLoad) => {
@@ -114,15 +130,22 @@ const I18nContextProvider = ({
       const { prefix, ...values } = trad
       const preparedValues = prefix ? prefixKeys(`${prefix}.`)(values) : values
 
-      setTranslations(prevState => ({
-        ...prevState,
-        ...{
-          [currentLocale]: {
-            ...prevState[currentLocale],
-            ...preparedValues,
+      // avoid a lot of render when async update
+      ReactDOM.unstable_batchedUpdates(() => {
+        setTranslations(prevState => ({
+          ...prevState,
+          ...{
+            [currentLocale]: {
+              ...prevState[currentLocale],
+              ...preparedValues,
+            },
           },
-        },
-      }))
+        }))
+
+        setNamespaces(prevState => [
+          ...new Set([...(prevState || []), namespace]),
+        ])
+      })
 
       return namespace
     },
@@ -131,12 +154,12 @@ const I18nContextProvider = ({
 
   const switchLocale = useCallback(
     locale => {
-      if (locales.includes(locale)) {
+      if (supportedLocales.includes(locale)) {
         localStorage.setItem(localeItemStorage, locale)
         setCurrentLocale(locale)
       }
     },
-    [setCurrentLocale, locales, localeItemStorage],
+    [localeItemStorage, setCurrentLocale, supportedLocales],
   )
 
   const formatNumber = useCallback(
@@ -205,14 +228,6 @@ const I18nContextProvider = ({
     [translate],
   )
 
-  useEffect(() => {
-    loadDateLocale(currentLocale === 'en' ? 'en-GB' : currentLocale)
-      .then(setDateFnsLocale)
-      .catch(() => loadDateLocale('en-GB').then(setDateFnsLocale))
-
-    setCurrentLocale(getCurrentLocale())
-  }, [loadDateLocale, currentLocale, getCurrentLocale])
-
   const value = useMemo(
     () => ({
       currentLocale,
@@ -221,11 +236,11 @@ const I18nContextProvider = ({
       formatList,
       formatNumber,
       loadTranslations,
-      locales,
+      locales: supportedLocales,
       namespaceTranslation,
+      namespaces,
       relativeTime,
       relativeTimeStrict,
-      setLocales,
       setTranslations,
       switchLocale,
       t: translate,
@@ -235,15 +250,15 @@ const I18nContextProvider = ({
       currentLocale,
       dateFnsLocale,
       datetime,
-      formatNumber,
       formatList,
+      formatNumber,
       loadTranslations,
-      locales,
       namespaceTranslation,
+      namespaces,
       relativeTime,
       relativeTimeStrict,
-      setLocales,
       setTranslations,
+      supportedLocales,
       switchLocale,
       translate,
       translations,

diff --git a/yarn.lock b/yarn.lock
@@ -126,16 +126,7 @@
   dependencies:
     "@babel/types" "^7.12.13"
 
-"@babel/helper-function-name@^7.12.13":
-  version "7.12.13"
-  resolved "https://registry.yarnpkg.com/@babel/helper-function-name/-/helper-function-name-7.12.13.tgz#93ad656db3c3c2232559fd7b2c3dbdcbe0eb377a"
-  integrity sha512-TZvmPn0UOqmvi5G4vvw0qZTpVptGkB1GL61R6lKvrSdIxGm5Pky7Q3fpKiIkQCAtRCBUwB0PaThlx9vebCDSwA==
-  dependencies:
-    "@babel/helper-get-function-arity" "^7.12.13"
-    "@babel/template" "^7.12.13"
-    "@babel/types" "^7.12.13"
-
-"@babel/helper-function-name@^7.14.2":
+"@babel/helper-function-name@^7.12.13", "@babel/helper-function-name@^7.14.2":
   version "7.14.2"
   resolved "https://registry.yarnpkg.com/@babel/helper-function-name/-/helper-function-name-7.14.2.tgz#397688b590760b6ef7725b5f0860c82427ebaac2"
   integrity sha512-NYZlkZRydxw+YT56IlhIcS8PAhb+FEUiOzuhFTfqDyPmzAhRge6ua0dQYT/Uh0t/EDHq05/i+e5M2d4XvjgarQ==
@@ -6552,12 +6543,12 @@ ms@2.0.0:
   resolved "https://registry.yarnpkg.com/ms/-/ms-2.0.0.tgz#5608aeadfc00be6c2901df5f9861788de0d597c8"
   integrity sha1-VgiurfwAvmwpAd9fmGF4jeDVl8g=
 
-ms@2.1.2, ms@^2.0.0:
+ms@2.1.2:
   version "2.1.2"
   resolved "https://registry.yarnpkg.com/ms/-/ms-2.1.2.tgz#d09d1f357b443f493382a8eb3ccd183872ae6009"
   integrity sha512-sGkPx+VjMtmA6MX27oA4FBFELFCZZ4S4XqeGOXCv68tT+jb3vk/RyaKWP0PTKyWtmLSM0b+adUTEvbs1PEaH2w==
 
-ms@^2.1.1:
+ms@^2.0.0, ms@^2.1.1:
   version "2.1.3"
   resolved "https://registry.yarnpkg.com/ms/-/ms-2.1.3.tgz#574c8138ce1d2b5861f0b44579dbadd60c6615b2"
   integrity sha512-6FlzubTLZG3J2a/NVCAleEhjzq5oxgHyaCU9yYXvcLsvoVaHJq/s5xXI6/XXP6tz7R9xAOtHnSO/tXtF3WRTlA==
@@ -7269,12 +7260,7 @@ performance-now@^2.1.0:
   resolved "https://registry.yarnpkg.com/performance-now/-/performance-now-2.1.0.tgz#6309f4e0e5fa913ec1c69307ae364b4b377c9e7b"
   integrity sha1-Ywn04OX6kT7BxpMHrjZLSzd8nns=
 
-picomatch@^2.0.4, picomatch@^2.2.1, picomatch@^2.2.2:
-  version "2.2.2"
-  resolved "https://registry.yarnpkg.com/picomatch/-/picomatch-2.2.2.tgz#21f333e9b6b8eaff02468f5146ea406d345f4dad"
-  integrity sha512-q0M/9eZHzmr0AulXyPwNfZjtwZ/RBZlbN3K3CErVrk50T2ASYI7Bye0EvekFY3IP1Nt2DHu0re+V2ZHIpMkuWg==
-
-picomatch@^2.2.3:
+picomatch@^2.0.4, picomatch@^2.2.1, picomatch@^2.2.2, picomatch@^2.2.3:
   version "2.2.3"
   resolved "https://registry.yarnpkg.com/picomatch/-/picomatch-2.2.3.tgz#465547f359ccc206d3c48e46a1bcb89bf7ee619d"
   integrity sha512-KpELjfwcCDUb9PeigTs2mBJzXUPzAuP2oPcA989He8Rte0+YUAjw1JVedDhuTKPkHjSYzMN3npC9luThGYEKdg==
@@ -7486,7 +7472,7 @@ quick-lru@^4.0.1:
   resolved "https://registry.yarnpkg.com/quick-lru/-/quick-lru-4.0.1.tgz#5b8878f113a58217848c6482026c73e1ba57727f"
   integrity sha512-ARhCpm70fzdcvNQfPoy49IaanKkTlRWF2JMzqhcJbhSFRZv7nPTvZJdcY7301IPmvW+/p0RgIWnQDLJxifsQ7g==
 
-react-dom@^17.0.1:
+react-dom@17.0.2, react-dom@^17.0.1:
   version "17.0.2"
   resolved "https://registry.yarnpkg.com/react-dom/-/react-dom-17.0.2.tgz#ecffb6845e3ad8dbfcdc498f0d0a939736502c23"
   integrity sha512-s4h96KtLDUQlsENhMn1ar8t2bEa+q/YAtj8pPPdIjPDGBDIVNsrD9aXNWqspUe6AzKCIG0C1HZZLqLV7qpOBGA==
@@ -7980,14 +7966,7 @@ run-parallel@^1.1.9:
   dependencies:
     queue-microtask "^1.2.2"
 
-rxjs@^6.6.0:
-  version "6.6.6"
-  resolved "https://registry.yarnpkg.com/rxjs/-/rxjs-6.6.6.tgz#14d8417aa5a07c5e633995b525e1e3c0dec03b70"
-  integrity sha512-/oTwee4N4iWzAMAL9xdGKjkEHmIwupR3oXbQjCKywF1BeFohswF3vZdogbmEF6pZkOsXTzWkrZszrWpQTByYVg==
-  dependencies:
-    tslib "^1.9.0"
-
-rxjs@^6.6.7:
+rxjs@^6.6.0, rxjs@^6.6.7:
   version "6.6.7"
   resolved "https://registry.yarnpkg.com/rxjs/-/rxjs-6.6.7.tgz#90ac018acabf491bf65044235d5863c4dab804c9"
   integrity sha512-hTdwr+7yYNIT5n4AMYp85KA6yw2Va0FLa3Rguvbpa4W3I5xynaBZo41cM3XM+4Q6fRMj3sBYIR1VAmZMXYJvRQ==