@venuu/i18n-js-webpack-plugin/lib/minimize-translations.js

webpack companion plugin for i18n-js to include only used translations

/* @flow */

const { set, view, lensPath } = require("ramda");
const uniq = require("lodash/uniq");

const flatten = arrays => [].concat(...arrays);

/*::
type Locale = string;
type TranslationLeafNode = string | number | boolean | null;
type Translation = TranslationLeafNode | Array<TranslationLeafNode> | { [key: string]: Translation };
type Translations = { [locale: Locale]: { [key: string]: Translation } }
type Options = {|
  fullTranslations: Translations
|};
*/

function keypathsWithLocales(
  keypaths /*: Array<string>*/,
  locales /*: Array<string>*/
) /*: Array<string> */ {
  return flatten(
    uniq(keypaths)
      .map(keypath => locales.map(locale => `${locale}.${keypath}`))
      // Keep the order of emitted JSON consistent by sorting the keypaths
      .sort()
  );
}

module.exports = function makeTranslationGraphMinimizer(
  { fullTranslations } /*: Options */
) {
  const locales = Object.keys(fullTranslations);

  return function pickUsedTranslations(
    usedTranslationKeypaths /*: Array<string> */
  ) {
    // For each used keypath, pick the corresponding value in the fullTranslations graph
    // into minimizedTranslations
    return (
      keypathsWithLocales(usedTranslationKeypaths, locales)
        // $FlowFixMe ramda types get mixed up here
        .map(keypath => lensPath(keypath.split(".")))
        .reduce((minimizedTranslations, translationLens) => {
          const translation = view(translationLens, fullTranslations);
          return set(translationLens, translation, minimizedTranslations);
        }, {})
    );
  };
};