react-i18n - add from-dictionary-index plugin mode

.travis.yml

@@ -15,7 +15,7 @@ matrix:
     - <<: *node_container
       name: 'Node - build, type-check, and end-to-end tests'
       script:
-        - yarn build
+        - yarn build --verbose
         - yarn test --testPathPattern react-server-webpack-plugin address
     - <<: *node_container
       name: 'Node - unit tests'

packages/react-i18n/CHANGELOG.md

@@ -6,7 +6,11 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 
 ---
 
-<!-- ## [Unreleased] -->
+## [Unreleased]
+
+### Added
+
+- Minor - added a `generateTranslationDictionaries` helper, and `mode=from-dictionary-index` option for the Babel plugin. This can be used to build many versions of an application, with each version containing a specific locale's translations directly within JavaScript ([#1197](https://github.com/Shopify/quilt/pull/1197/files))
 
 ## [2.2.0] - 2019-11-22
 

packages/react-i18n/README.md

@@ -409,22 +409,80 @@ Because `babel-loader`'s cache is based on a component's source content hash, ne
 The generator will look for any `translations` folders and generate an array of local ids in `translations/index.js` based on the `{locale}.json` files found. We recommend that you add `**/translations/index.js` to `.gitignore` to make sure the generated files are not checked-in.
 
 ```js
-// babel.config.js
+// webpack.config.js
+module.exports = {
+  resolve: {
+    extensions: ['.js', '.jsx'],
+  },
+  module: {
+    rules: [
+      {
+        test: /\.jsx?$/,
+        use: [
+          {
+            loader: 'babel-loader',
+            options: {
+              plugins: [
+                '@babel/plugin-syntax-dynamic-import',
+                ['@shopify/react-i18n/babel', {mode: 'from-generated-index'}],
+              ],
+            },
+          },
+        ],
+      },
+    ],
+  },
+};
+```
+
+```js
+// generate-translations.js
+const {
+  generateTranslationIndexes,
+} = require('@shopify/react-i18n/generate-index');
+
+generateTranslationIndexes();
+webpack(require(./webpack.config.js));
+```
+
+#### Statically embedding locale-specific translations
+
+For large applications, even asynchronously loaded translations can significantly degrade the user experience:
+
+- Bundlers like webpack have to embed kilobytes of data to track each translation import
+- Users not using the "default" language have to download kilobytes of translations for every language
+
+To avoid this, it is possible to build versions of app with specific locale translations embedded directly in JavaScript. To achieve this, run the Babel plugin in `from-dictionary-index` mode:
+
+```js
+// webpack.config.js
 {
   plugins: [
-    ['@shopify/react-i18n/babel', {mode: 'from-generated-index'}],
+    ['@shopify/react-i18n/babel', {mode: 'from-dictionary-index'}],
   ],
 }
 ```
 
+Then generate `translations/index.js` files containing specific locale data using the `@shopify/react-i18n/generate-dictionaries` helper. e.g., the following code generates three versions of an application with English, French, and German content using webpack.
+
 ```js
 // generate-translations.js
 const {
-  generateTranslationIndexes,
-} = require('@shopify/react-i18n/generate-index');
+  generateTranslationDictionaries,
+} = require('@shopify/react-i18n/generate-dictionaries');
 
-generateTranslationIndexes();
+// Build English app.
+await generateTranslationDictionaries(['en']);
+webpack(require(./webpack.config.js));
+
+// Build French app.
+await generateTranslationDictionaries(['fr'], {fallbackLocale: 'en'});
 webpack(require(./webpack.config.js));
+
+// Build German app.
+await generateTranslationDictionaries(['de'], {fallbackLocale: 'en'});
+webpack(require(./webpack.config.js));
+
 ```
 
 ## FAQ

packages/react-i18n/generate-dictionaries.d.ts

@@ -0,0 +1,4 @@
+export {
+  generateTranslationDictionaries,
+} from './dist/src/babel-plugin/generate-dictionaries';
+export * from './dist/src/babel-plugin/generate-dictionaries';

packages/react-i18n/generate-dictionaries.js

@@ -0,0 +1 @@
+module.exports = require('./dist/src/babel-plugin/generate-dictionaries');

packages/react-i18n/package.json

@@ -42,6 +42,8 @@
     "@types/hoist-non-react-statics": "^3.0.1",
     "change-case": "^3.1.0",
     "glob": "^7.1.4",
+    "lodash.clonedeep": "^4.0.0",
+    "lodash.merge": "^4.0.0",
     "hoist-non-react-statics": "^3.0.1",
     "prop-types": "^15.6.2",
     "string-hash": "^1.1.3",
@@ -61,6 +63,8 @@
     "babel.d.ts",
     "babel.js",
     "generate-index.d.ts",
-    "generate-index.js"
+    "generate-index.js",
+    "generate-dictionaries.d.ts",
+    "generate-dictionaries.js"
   ]
 }

packages/react-i18n/src/babel-plugin/babel-templates.ts

@@ -69,3 +69,23 @@ export function i18nCallExpression(
     },
   )();
 }
+
+export function i18nGeneratedDictionaryCallExpression(
+  template: TemplateBuilder<Types.ImportDeclaration | Types.ObjectExpression>,
+  {id, translationsID, bindingName},
+) {
+  return template(
+    `${bindingName}({
+        id: '${id}',
+        fallback: Object.values(${translationsID})[0],
+        translations(locale) {
+          return Promise.resolve(${translationsID}[locale]);
+        },
+      })`,
+    {
+      sourceType: 'module',
+      plugins: ['dynamicImport'],
+      preserveComments: true,
+    },
+  )();
+}

packages/react-i18n/src/babel-plugin/generate-dictionaries.ts

@@ -0,0 +1,74 @@
+import {join} from 'path';
+
+import fs from 'fs-extra';
+import cloneDeep from 'lodash.clonedeep';
+import merge from 'lodash.merge';
+
+import {DEFAULT_FALLBACK_LOCALE, findTranslationBuckets} from './shared';
+
+export interface Options {
+  fallbackLocale: string;
+  rootDir: string;
+}
+
+export async function generateTranslationDictionaries(
+  locales: string[],
+  {
+    fallbackLocale = DEFAULT_FALLBACK_LOCALE,
+    rootDir = process.cwd(),
+  }: Partial<Options> = {},
+) {
+  if (!locales || locales.length === 0) {
+    throw new Error(
+      'generateTranslationDictionary must be called with at least one locale.',
+    );
+  }
+
+  const translationBuckets = findTranslationBuckets(rootDir);
+
+  await Promise.all(
+    Object.entries(translationBuckets).map(
+      async ([translationsDir, translationFilePaths]) => {
+        const fallbackTranslations = await readLocaleTranslations(
+          fallbackLocale,
+          translationFilePaths,
+        );
+
+        const dictionary = await locales.reduce(async (accPromise, locale) => {
+          const localeTranslations = await readLocaleTranslations(
+            locale,
+            translationFilePaths,
+          );
+          const acc = await accPromise;
+          acc[locale] = merge(
+            cloneDeep(fallbackTranslations),
+            localeTranslations,
+          );
+          return acc;
+        }, {});
+
+        const contentStr = JSON.stringify(dictionary);
+
+        // Writing the content out as a JSON.parse-wrapped string seems
+        // counter-intuitive, but browsers can parse this faster than they
+        // can parse JavaScript ‾\_(ツ)_/‾
+        // https://www.youtube.com/watch?v=ff4fgQxPaO0
+        await fs.writeFile(
+          join(translationsDir, 'index.js'),
+          `export default JSON.parse(${JSON.stringify(contentStr)})`,
+        );
+      },
+    ),
+  );
+}
+
+async function readLocaleTranslations(
+  locale: string,
+  translationFilePaths: string[],
+) {
+  const translationPath = translationFilePaths.find(filePath =>
+    filePath.endsWith(`/${locale}.json`),
+  );
+
+  return translationPath ? fs.readJson(translationPath) : {};
+}

packages/react-i18n/src/babel-plugin/generate-index.ts

@@ -1,37 +1,22 @@
-import {execSync} from 'child_process';
-import {dirname, join} from 'path';
+import {join} from 'path';
 
 import fs from 'fs-extra';
 
 import {
-  TRANSLATION_DIRECTORY_NAME,
   DEFAULT_FALLBACK_LOCALE,
+  findTranslationBuckets,
   getLocaleIds,
   toArrayString,
 } from './shared';
 
+export interface Options {
+  fallbackLocale: string;
+  rootDir: string;
+}
+
 export function generateTranslationIndexes() {
   const fallbackLocale = DEFAULT_FALLBACK_LOCALE;
-
-  // `find` is used here instead of Node's glob because it performs much faster
-  // (20s vs 1s in web with ~750 translation folders and 21 langs)
-  const files = execSync(
-    `find . -type d \\( -path ./node_modules -o -path ./build -o -path ./tmp -o -path ./.git -o -path ./public \\) -prune -o -name '*.json' -print | grep /${TRANSLATION_DIRECTORY_NAME}/`,
-  )
-    .toString()
-    .trim()
-    .split('\n')
-    .sort();
-
-  const translationBuckets = files.reduce((acc, translationPath) => {
-    const translationsDir = dirname(translationPath);
-    if (!acc[translationsDir]) {
-      acc[translationsDir] = [];
-    }
-
-    acc[translationsDir].push(translationPath);
-    return acc;
-  }, {});
+  const translationBuckets = findTranslationBuckets(process.cwd());
 
   Object.entries(translationBuckets).forEach(
     ([translationsDir, translationFilePaths]: [string, string[]]) => {