hooks/pre-build.js

var fs = require('fs-extra');
var jsonConcat = require("json-concat");

var localizationSourceFilesEN = [
  "./i18n/general.de.json",
  "./i18n/components.de.json",
  "./i18n/contacts.en.json",
  "./i18n/salutations.en.json"
  "./i18n/persons.de.json",
];

var localizationSourceFilesDE = [
  "./i18n/general.de.json",
  "./i18n/components.de.json",
  "./i18n/contacts.de.json",
  "./i18n/persons.de.json",
  "./i18n/salutations.de.json"
];

function mergeAndSaveJsonFiles(src, dest) {
  jsonConcat({ src: src, dest: dest },
    function (res) {
      console.log('Localization files successfully merged!');
    }
  );
}

function setEnvironment(configPath, environment) {
  fs.writeJson(configPath, {env: environment},
    function (res) {
      console.log('Environment variable set to ' + environment)
    }
  );
}

// Set environment variable to "production"
setEnvironment('./src/config/env.json', 'production');

// Merge all localization files into one
mergeAndSaveJsonFiles(localizationSourceFilesEN, "./src/i18n/en.json");
mergeAndSaveJsonFiles(localizationSourceFilesDE, "./src/i18n/de.json");