use arrow functions where possible

src/TransWithoutContext.js

@@ -4,36 +4,34 @@ import { warn, warnOnce } from './utils.js';
 import { getDefaults } from './defaults.js';
 import { getI18n } from './i18nInstance.js';
 
-function hasChildren(node, checkLength) {
+const hasChildren = (node, checkLength) => {
   if (!node) return false;
   const base = node.props ? node.props.children : node.children;
   if (checkLength) return base.length > 0;
   return !!base;
-}
+};
 
-function getChildren(node) {
+const getChildren = (node) => {
   if (!node) return [];
   const children = node.props ? node.props.children : node.children;
   return node.props && node.props.i18nIsDynamicList ? getAsArray(children) : children;
-}
+};
 
-function hasValidReactChildren(children) {
+const hasValidReactChildren = (children) => {
   if (Object.prototype.toString.call(children) !== '[object Array]') return false;
   return children.every((child) => isValidElement(child));
-}
+};
 
-function getAsArray(data) {
-  return Array.isArray(data) ? data : [data];
-}
+const getAsArray = (data) => (Array.isArray(data) ? data : [data]);
 
-function mergeProps(source, target) {
+const mergeProps = (source, target) => {
   const newTarget = { ...target };
   // overwrite source.props when target.props already set
   newTarget.props = Object.assign(source.props, target.props);
   return newTarget;
-}
+};
 
-export function nodesToString(children, i18nOptions) {
+export const nodesToString = (children, i18nOptions) => {
   if (!children) return '';
   let stringNode = '';
 
@@ -103,9 +101,9 @@ export function nodesToString(children, i18nOptions) {
   });
 
   return stringNode;
-}
+};
 
-function renderNodes(children, targetString, i18n, i18nOptions, combinedTOpts, shouldUnescape) {
+const renderNodes = (children, targetString, i18n, i18nOptions, combinedTOpts, shouldUnescape) => {
   if (targetString === '') return [];
 
   // check if contains tags we need to replace from html string to react nodes
@@ -119,15 +117,15 @@ function renderNodes(children, targetString, i18n, i18nOptions, combinedTOpts, s
   // v2 -> interpolates upfront no need for "some <0>{{var}}</0>"" -> will be just "some {{var}}" in translation file
   const data = {};
 
-  function getData(childs) {
+  const getData = (childs) => {
     const childrenArray = getAsArray(childs);
 
     childrenArray.forEach((child) => {
       if (typeof child === 'string') return;
       if (hasChildren(child)) getData(getChildren(child));
       else if (typeof child === 'object' && !isValidElement(child)) Object.assign(data, child);
     });
-  }
+  };
 
   getData(children);
 
@@ -136,7 +134,7 @@ function renderNodes(children, targetString, i18n, i18nOptions, combinedTOpts, s
   const ast = HTML.parse(`<0>${targetString}</0>`);
   const opts = { ...data, ...combinedTOpts };
 
-  function renderInner(child, node, rootReactNode) {
+  const renderInner = (child, node, rootReactNode) => {
     const childs = getChildren(child);
     const mappedChildren = mapAST(childs, node.children, rootReactNode);
     // `mappedChildren` will always be empty if using the `i18nIsDynamicList` prop,
@@ -145,9 +143,9 @@ function renderNodes(children, targetString, i18n, i18nOptions, combinedTOpts, s
       (child.props && child.props.i18nIsDynamicList)
       ? childs
       : mappedChildren;
-  }
+  };
 
-  function pushTranslatedJSX(child, inner, mem, i, isVoid) {
+  const pushTranslatedJSX = (child, inner, mem, i, isVoid) => {
     if (child.dummy) {
       child.children = inner; // needed on preact!
       mem.push(cloneElement(child, { key: i }, isVoid ? undefined : inner));
@@ -169,12 +167,12 @@ function renderNodes(children, targetString, i18n, i18nOptions, combinedTOpts, s
         }),
       );
     }
-  }
+  };
 
   // reactNode (the jsx root element or child)
   // astNode (the translation string as html ast)
   // rootReactNode (the most outer jsx children array or trans components prop)
-  function mapAST(reactNode, astNode, rootReactNode) {
+  const mapAST = (reactNode, astNode, rootReactNode) => {
     const reactNodes = getAsArray(reactNode);
     const astNodes = getAsArray(astNode);
 
@@ -291,7 +289,7 @@ function renderNodes(children, targetString, i18n, i18nOptions, combinedTOpts, s
       }
       return mem;
     }, []);
-  }
+  };
 
   // call mapAST with having react nodes nested into additional node like
   // we did for the string ast from translation
@@ -302,7 +300,7 @@ function renderNodes(children, targetString, i18n, i18nOptions, combinedTOpts, s
     getAsArray(children || []),
   );
   return getChildren(result[0]);
-}
+};
 
 export function Trans({
   children,

src/context.js

@@ -18,27 +18,23 @@ export class ReportNamespaces {
     });
   }
 
-  getUsedNamespaces() {
-    return Object.keys(this.usedNamespaces);
-  }
+  getUsedNamespaces = () => Object.keys(this.usedNamespaces);
 }
 
-export function composeInitialProps(ForComponent) {
-  return async (ctx) => {
-    const componentsInitialProps = ForComponent.getInitialProps
-      ? await ForComponent.getInitialProps(ctx)
-      : {};
+export const composeInitialProps = (ForComponent) => async (ctx) => {
+  const componentsInitialProps = ForComponent.getInitialProps
+    ? await ForComponent.getInitialProps(ctx)
+    : {};
 
-    const i18nInitialProps = getInitialProps();
+  const i18nInitialProps = getInitialProps();
 
-    return {
-      ...componentsInitialProps,
-      ...i18nInitialProps,
-    };
+  return {
+    ...componentsInitialProps,
+    ...i18nInitialProps,
   };
-}
+};
 
-export function getInitialProps() {
+export const getInitialProps = () => {
   const i18n = getI18n();
   const namespaces = i18n.reportNamespaces ? i18n.reportNamespaces.getUsedNamespaces() : [];
 
@@ -55,4 +51,4 @@ export function getInitialProps() {
   ret.initialLanguage = i18n.language;
 
   return ret;
-}
+};

src/defaults.js

@@ -13,10 +13,8 @@ let defaultOptions = {
   unescape,
 };
 
-export function setDefaults(options = {}) {
+export const setDefaults = (options = {}) => {
   defaultOptions = { ...defaultOptions, ...options };
-}
+};
 
-export function getDefaults() {
-  return defaultOptions;
-}
+export const getDefaults = () => defaultOptions;

src/i18nInstance.js

@@ -1,9 +1,7 @@
 let i18nInstance;
 
-export function setI18n(instance) {
+export const setI18n = (instance) => {
   i18nInstance = instance;
-}
+};
 
-export function getI18n() {
-  return i18nInstance;
-}
+export const getI18n = () => i18nInstance;

src/useSSR.js

@@ -1,7 +1,7 @@
 import { useContext } from 'react';
 import { getI18n, I18nContext } from './context.js';
 
-export function useSSR(initialI18nStore, initialLanguage, props = {}) {
+export const useSSR = (initialI18nStore, initialLanguage, props = {}) => {
   const { i18n: i18nFromProps } = props;
   const { i18n: i18nFromContext } = useContext(I18nContext) || {};
   const i18n = i18nFromProps || i18nFromContext || getI18n();
@@ -30,4 +30,4 @@ export function useSSR(initialI18nStore, initialLanguage, props = {}) {
     i18n.changeLanguage(initialLanguage);
     i18n.initializedLanguageOnce = true;
   }
-}
+};

src/useTranslation.js

@@ -10,20 +10,18 @@ const usePrevious = (value, ignore) => {
   return ref.current;
 };
 
-function alwaysNewT(i18n, language, namespace, keyPrefix) {
-  return i18n.getFixedT(language, namespace, keyPrefix);
-}
+const alwaysNewT = (i18n, language, namespace, keyPrefix) =>
+  i18n.getFixedT(language, namespace, keyPrefix);
 
-function useMemoizedT(i18n, language, namespace, keyPrefix) {
-  return useCallback(alwaysNewT(i18n, language, namespace, keyPrefix), [
+const useMemoizedT = (i18n, language, namespace, keyPrefix) =>
+  useCallback(alwaysNewT(i18n, language, namespace, keyPrefix), [
     i18n,
     language,
     namespace,
     keyPrefix,
   ]);
-}
 
-export function useTranslation(ns, props = {}) {
+export const useTranslation = (ns, props = {}) => {
   // assert we have the needed i18nInstance
   const { i18n: i18nFromProps } = props;
   const { i18n: i18nFromContext, defaultNS: defaultNSFromContext } = useContext(I18nContext) || {};
@@ -114,9 +112,9 @@ export function useTranslation(ns, props = {}) {
       setT(getNewT);
     }
 
-    function boundReset() {
+    const boundReset = () => {
       if (isMounted.current) setT(getNewT);
-    }
+    };
 
     // bind events to trigger change, like languageChanged
     if (bindI18n && i18n) i18n.on(bindI18n, boundReset);
@@ -161,4 +159,4 @@ export function useTranslation(ns, props = {}) {
       loadNamespaces(i18n, namespaces, () => resolve());
     }
   });
-}
+};

src/utils.js

@@ -1,3 +1,4 @@
+// Do not use arrow function here as it will break optimizations of arguments
 export function warn(...args) {
   if (console && console.warn) {
     if (typeof args[0] === 'string') args[0] = `react-i18next:: ${args[0]}`;
@@ -6,6 +7,7 @@ export function warn(...args) {
 }
 
 const alreadyWarned = {};
+// Do not use arrow function here as it will break optimizations of arguments
 export function warnOnce(...args) {
   if (typeof args[0] === 'string' && alreadyWarned[args[0]]) return;
   if (typeof args[0] === 'string') alreadyWarned[args[0]] = new Date();
@@ -37,22 +39,22 @@ const loadedClb = (i18n, cb) => () => {
   }
 };
 
-export function loadNamespaces(i18n, ns, cb) {
+export const loadNamespaces = (i18n, ns, cb) => {
   i18n.loadNamespaces(ns, loadedClb(i18n, cb));
-}
+};
 
 // should work with I18NEXT >= v22.5.0
-export function loadLanguages(i18n, lng, ns, cb) {
+export const loadLanguages = (i18n, lng, ns, cb) => {
   // eslint-disable-next-line no-param-reassign
   if (typeof ns === 'string') ns = [ns];
   ns.forEach((n) => {
     if (i18n.options.ns.indexOf(n) < 0) i18n.options.ns.push(n);
   });
   i18n.loadLanguages(lng, loadedClb(i18n, cb));
-}
+};
 
 // WAIT A LITTLE FOR I18NEXT BEING UPDATED IN THE WILD, before removing this old i18next version support
-function oldI18nextHasLoadedNamespace(ns, i18n, options = {}) {
+const oldI18nextHasLoadedNamespace = (ns, i18n, options = {}) => {
   const lng = i18n.languages[0];
   const fallbackLng = i18n.options ? i18n.options.fallbackLng : false;
   const lastLng = i18n.languages[i18n.languages.length - 1];
@@ -91,9 +93,9 @@ function oldI18nextHasLoadedNamespace(ns, i18n, options = {}) {
   if (loadNotPending(lng, ns) && (!fallbackLng || loadNotPending(lastLng, ns))) return true;
 
   return false;
-}
+};
 
-export function hasLoadedNamespace(ns, i18n, options = {}) {
+export const hasLoadedNamespace = (ns, i18n, options = {}) => {
   if (!i18n.languages || !i18n.languages.length) {
     warnOnce('i18n.languages were undefined or empty', i18n.languages);
     return true;
@@ -120,12 +122,9 @@ export function hasLoadedNamespace(ns, i18n, options = {}) {
         return false;
     },
   });
-}
+};
 
-export function getDisplayName(Component) {
-  return (
-    Component.displayName ||
-    Component.name ||
-    (typeof Component === 'string' && Component.length > 0 ? Component : 'Unknown')
-  );
-}
+export const getDisplayName = (Component) =>
+  Component.displayName ||
+  Component.name ||
+  (typeof Component === 'string' && Component.length > 0 ? Component : 'Unknown');

src/withSSR.js

@@ -3,8 +3,8 @@ import { useSSR } from './useSSR.js';
 import { composeInitialProps } from './context.js';
 import { getDisplayName } from './utils.js';
 
-export function withSSR() {
-  return function Extend(WrappedComponent) {
+export const withSSR = () =>
+  function Extend(WrappedComponent) {
     function I18nextWithSSR({ initialI18nStore, initialLanguage, ...rest }) {
       useSSR(initialI18nStore, initialLanguage);
 
@@ -19,4 +19,3 @@ export function withSSR() {
 
     return I18nextWithSSR;
   };
-}

src/withTranslation.js

@@ -2,8 +2,8 @@ import { createElement, forwardRef as forwardRefReact } from 'react';
 import { useTranslation } from './useTranslation.js';
 import { getDisplayName } from './utils.js';
 
-export function withTranslation(ns, options = {}) {
-  return function Extend(WrappedComponent) {
+export const withTranslation = (ns, options = {}) =>
+  function Extend(WrappedComponent) {
     function I18nextWithTranslation({ forwardedRef, ...rest }) {
       const [t, i18n, ready] = useTranslation(ns, { ...rest, keyPrefix: options.keyPrefix });
 
@@ -33,4 +33,3 @@ export function withTranslation(ns, options = {}) {
 
     return options.withRef ? forwardRefReact(forwardRef) : I18nextWithTranslation;
   };
-}