send/app/locale.js

import { FluentBundle } from 'fluent';

function makeBundle(locale, ftl) {
  const bundle = new FluentBundle(locale, { useIsolating: false });
  bundle.addMessages(ftl);
  return bundle;
}

export async function getTranslator(locale) {
  const bundles = [];
  const { default: en } = await import('../public/locales/en-US/send.ftl');
  if (locale !== 'en-US') {
    const {
      default: ftl
    } = await import(`../public/locales/${locale}/send.ftl`);
    bundles.push(makeBundle(locale, ftl));
  }
  bundles.push(makeBundle('en-US', en));
  return function(id, data) {
    for (let bundle of bundles) {
      if (bundle.hasMessage(id)) {
        return bundle.format(bundle.getMessage(id), data);
      }
    }
  };
}