Rewrite with Typescript

package.json

@@ -12,9 +12,9 @@
   "author": "Netcetera AG",
   "license": "MIT",
   "repository": "https://github.com/netceteragroup/react-message-source",
-  "main": "dist/index.js",
-  "module": "dist/index.es.js",
-  "jsnext:main": "dist/index.es.js",
+  "main": "dist/react-message-source.js",
+  "module": "dist/react-message-source.es.js",
+  "jsnext:main": "dist/react-message-source.es.js",
   "engines": {
     "node": ">=8",
     "npm": ">=5"
@@ -23,6 +23,7 @@
     "test": "cross-env CI=1 react-scripts test --env=jsdom",
     "test:watch": "react-scripts test --env=jsdom",
     "coverage": "cross-env CI=1 react-scripts test --coverage --coverageReporters=text-lcov | coveralls",
+    "prebuild": "rimraf dist",
     "build": "rollup -c",
     "start": "rollup -c -w",
     "prepare": "yarn run build",
@@ -37,31 +38,34 @@
     "react": "^16.8.0"
   },
   "devDependencies": {
-    "@babel/core": "^7.3.4",
-    "@babel/plugin-proposal-class-properties": "^7.3.4",
-    "@babel/preset-env": "^7.3.4",
-    "@babel/preset-react": "^7.0.0",
+    "@types/hoist-non-react-statics": "^3.3.0",
+    "@types/invariant": "^2.2.29",
+    "@types/jest": "^24.0.11",
+    "@types/react": "^16.8.8",
+    "@types/react-dom": "^16.8.2",
+    "@types/react-test-renderer": "^16.8.1",
     "coveralls": "^3.0.3",
     "cross-env": "^5.2.0",
-    "eslint-config-airbnb": "^17.1.0",
-    "eslint-config-prettier": "^4.1.0",
-    "eslint-plugin-import": "^2.16.0",
-    "eslint-plugin-jsx-a11y": "^6.2.1",
-    "eslint-plugin-prettier": "^3.0.1",
-    "eslint-plugin-react": "^7.12.4",
-    "eslint-plugin-react-hooks": "^1.5.1",
     "prettier": "^1.16.4",
     "prop-types": "^15.7.2",
     "react": "^16.8.4",
     "react-dom": "^16.8.4",
     "react-scripts": "2.1.8",
     "react-test-renderer": "^16.8.4",
     "react-testing-library": "^6.0.0",
+    "rimraf": "^2.6.3",
     "rollup": "^1.6.0",
-    "rollup-plugin-babel": "^4.3.2",
     "rollup-plugin-commonjs": "^9.2.1",
     "rollup-plugin-node-resolve": "^4.0.1",
-    "rollup-plugin-peer-deps-external": "^2.2.0"
+    "rollup-plugin-peer-deps-external": "^2.2.0",
+    "rollup-plugin-typescript2": "^0.20.1",
+    "tslib": "^1.9.3",
+    "tslint": "^5.14.0",
+    "tslint-config-prettier": "^1.18.0",
+    "tslint-plugin-prettier": "^2.0.1",
+    "tslint-react": "^3.6.0",
+    "tslint-react-hooks": "^2.0.0",
+    "typescript": "^3.3.3333"
   },
   "files": [
     "dist"

rollup.config.js

@@ -1,28 +1,33 @@
-import babel from 'rollup-plugin-babel';
+import typescript from 'rollup-plugin-typescript2';
 import commonjs from 'rollup-plugin-commonjs';
 import external from 'rollup-plugin-peer-deps-external';
 import resolve from 'rollup-plugin-node-resolve';
 
 import pkg from './package.json';
 
 module.exports = {
-  input: 'src/index.js',
+  input: 'src/index.ts',
   output: [
     {
       file: pkg.main,
       format: 'cjs',
-      sourcemap: true,
+      exports: 'named',
+      sourcemap: true
     },
     {
       file: pkg.module,
       format: 'es',
-      sourcemap: true,
-    },
+      exports: 'named',
+      sourcemap: true
+    }
   ],
   plugins: [
     external(),
-    babel(),
     resolve(),
+    typescript({
+      rollupCommonJSResolveHack: true,
+      clean: true,
+    }),
     commonjs()
-  ].filter(Boolean),
+  ],
 };

src/lib/FetchingProvider.test.js → src/lib/FetchingProvider.test.tsx

@@ -1,16 +1,17 @@
-import React from 'react';
+import * as React from 'react';
 import * as RTL from 'react-testing-library';
 import { FetchingProvider } from './FetchingProvider';
 import { useMessageSource } from './useMessageSource';
 
 describe('FetchingProvider', () => {
-  const Spy = () => {
+  function Spy() {
     const { getMessage } = useMessageSource();
-    return getMessage('hello.world');
-  };
+    return <span>{getMessage('hello.world')}</span>;
+  }
 
   beforeEach(() => {
     // mock impl of fetch() API
+    // @ts-ignore
     global.fetch = jest.fn(() =>
       Promise.resolve({
         json: () =>
@@ -47,14 +48,15 @@ describe('FetchingProvider', () => {
     expect(transform).toHaveBeenCalled();
     expect(onFetchingStart).toHaveBeenCalled();
     expect(onFetchingEnd).toHaveBeenCalled();
+    // @ts-ignore
     expect(global.fetch).toHaveBeenCalledTimes(1);
   });
 
   it('fetches text resources when url prop changes', async () => {
     const transform = jest.fn(x => x);
     const onFetchingStart = jest.fn();
     const onFetchingEnd = jest.fn();
-    function TestComponent(props) {
+    function TestComponent(props: { url: string }) {
       return (
         <FetchingProvider
           url={props.url} // eslint-disable-line react/prop-types
@@ -82,6 +84,7 @@ describe('FetchingProvider', () => {
         }),
     );
 
+    // @ts-ignore
     expect(global.fetch).toHaveBeenCalledTimes(2);
     expect(transform).toHaveBeenCalledTimes(2);
     expect(onFetchingStart).toHaveBeenCalledTimes(2);
@@ -91,9 +94,10 @@ describe('FetchingProvider', () => {
   it('invokes onFetchingError lifecycle on network failure', async () => {
     const onFetchingError = jest.fn();
     const faultyFetch = jest.fn(() => Promise.reject(new Error('Failure')));
+    // @ts-ignore
     global.fetch = faultyFetch;
 
-    RTL.render(<FetchingProvider url="http://any.uri/texts" onFetchingError={onFetchingError} />);
+    RTL.render(<FetchingProvider url="http://any.uri/texts" onFetchingError={onFetchingError} children={null} />);
     await RTL.wait(); // until fetch() rejects
 
     expect(faultyFetch).toHaveBeenCalledTimes(1);

src/lib/FetchingProvider.js → src/lib/FetchingProvider.tsx

@@ -1,64 +1,20 @@
-import React from 'react';
-import PropTypes from 'prop-types';
-import { Provider } from './MessageSourceContext';
+import * as React from 'react';
+import { MessageSourceContextShape, Provider } from './MessageSourceContext';
 
-const identity = x => x;
+const identity = (x: any): any => x;
+const noop = () => {};
 
-const initialState = {
-  translations: {},
-  isFetching: false,
-};
-
-/**
- * A special <Provider /> which can load translations from remote URL
- * via a `GET` request and pass them down the component tree.
- */
-export function FetchingProvider(props) {
-  const { url, blocking, children, transform, onFetchingStart, onFetchingEnd, onFetchingError } = props;
-  const [{ translations, isFetching }, setState] = React.useState(initialState);
-
-  React.useEffect(() => {
-    let isStillMounted = true;
-
-    setState(state => ({ ...state, isFetching: true }));
-    onFetchingStart();
-
-    fetch(url)
-      .then(r => r.json())
-      .then(response => {
-        if (isStillMounted) {
-          setState({
-            translations: transform(response),
-            isFetching: false,
-          });
-          onFetchingEnd();
-        }
-      })
-      .catch(onFetchingError);
-
-    return () => {
-      isStillMounted = false;
-    };
-  }, [url]); // re-fetch only when url changes
-
-  const shouldRenderSubtree = !blocking || (blocking && !isFetching);
-  return <Provider value={translations}>{shouldRenderSubtree ? children : null}</Provider>;
-}
-
-FetchingProvider.propTypes = {
+export interface FetchingProviderApi {
   /**
    * The URL which serves the text messages.
-   * Required.
    */
-  url: PropTypes.string.isRequired,
+  url: string;
 
   /**
    * Makes the rendering of the sub-tree synchronous.
    * The components will not render until fetching of the text messages finish.
-   *
-   * Defaults to true.
    */
-  blocking: PropTypes.bool,
+  blocking?: boolean;
 
   /**
    * A function which can transform the response received from GET /props.url
@@ -69,33 +25,80 @@ FetchingProvider.propTypes = {
    *   return response.textMessages;
    * }
    */
-  transform: PropTypes.func,
+  transform?: (x: any) => MessageSourceContextShape;
 
   /**
    * Invoked when fetching of text messages starts.
    */
-  onFetchingStart: PropTypes.func,
+  onFetchingStart?: () => void;
 
   /**
    * Invoked when fetching of text messages finishes.
    */
-  onFetchingEnd: PropTypes.func,
+  onFetchingEnd?: () => void;
 
   /**
    * Invoked when fetching fails.
    */
-  onFetchingError: PropTypes.func,
+  onFetchingError?: (e: Error) => void;
 
   /**
    * Children.
    */
-  children: PropTypes.node,
+  children: React.ReactNode;
+}
+
+type State = {
+  translations: MessageSourceContextShape,
+  isFetching: boolean,
 };
 
-FetchingProvider.defaultProps = {
-  blocking: true,
-  transform: identity,
-  onFetchingStart: identity,
-  onFetchingEnd: identity,
-  onFetchingError: identity,
+const initialState: State = {
+  translations: {},
+  isFetching: false,
 };
+
+/**
+ * A special <Provider /> which can load translations from remote URL
+ * via a `GET` request and pass them down the component tree.
+ */
+export function FetchingProvider(props: FetchingProviderApi) {
+  const {
+    url,
+    children,
+    blocking = true,
+    transform = identity,
+    onFetchingStart = noop,
+    onFetchingEnd = noop,
+    onFetchingError = noop,
+  } = props;
+
+  const [{ translations, isFetching }, setState] = React.useState<State>(initialState);
+
+  React.useEffect(() => {
+    let isStillMounted = true;
+
+    setState(state => ({ ...state, isFetching: true }));
+    onFetchingStart();
+
+    fetch(url)
+      .then(r => r.json())
+      .then(response => {
+        if (isStillMounted) {
+          setState({
+            translations: transform(response),
+            isFetching: false,
+          });
+          onFetchingEnd();
+        }
+      })
+      .catch(onFetchingError);
+
+    return () => {
+      isStillMounted = false;
+    };
+  }, [url]); // re-fetch only when url changes
+
+  const shouldRenderSubtree = !blocking || (blocking && !isFetching);
+  return <Provider value={translations}>{shouldRenderSubtree ? children : null}</Provider>;
+}

src/lib/MessageSourceContext.js → src/lib/MessageSourceContext.ts

@@ -1,4 +1,8 @@
-import React from 'react';
+import * as React from 'react';
+
+export type MessageSourceContextShape = {
+  [key: string]: string,
+};
 
 /**
  * Initial Context value, an empty object.
@@ -8,7 +12,7 @@ const empty = {};
 /**
  * A React Context which holds the translations map.
  */
-const MessageSourceContext = React.createContext(empty);
+const MessageSourceContext = React.createContext<MessageSourceContextShape>(empty);
 MessageSourceContext.displayName = 'MessageSourceContext';
 
 /**