Sync json locale files

.sync.js

#!/usr/bin/env node
var fs = require("fs");

const readJson = (path) => {
  let raw = fs.readFileSync(path)
  try {
    return JSON.parse(raw)
  } catch (error) {
    return {}
  }
}

const defaultLocale = 'en-US.json'
const defaultData = readJson(defaultLocale)

const getFiles = (path) => {
  const fileNames = fs.readdirSync(path)
  const jsonFiles = fileNames.filter(file => /\.json$/.test(file) && file !== defaultLocale)
  const files = {}
  return jsonFiles.reduce((files, file) => {
    files[file] = readJson(`${path}${file}`)
    return files
  }, files)
}

const isString = (subject) => typeof subject === "string"
const isSameType = (a, b) => typeof a === typeof b

const sync = (data = {}, defaultData) => {
  for (key of Object.keys(defaultData)) {
    if (!(key in data)) {
      if (isString(defaultData[key])) {
        data[key] = ""
      } else {
        data[key] = sync(data[key], defaultData[key])
      }
    } else {
      if (!isSameType(data[key], defaultData[key])) {
        throw new Error(`Different types found for key "${key}". Aborting.`)
      }
      if (!isString(data[key])) {
        data[key] = sync(data[key], defaultData[key])
      }
    }
  }

  return data
}

const map = getFiles('./')

for (let [locale, data] of Object.entries(map)) {
  console.group(locale)
  console.log('Syncing...')
  let synced = JSON.stringify(sync(data, defaultData), null, 2)

  fs.writeFileSync(locale, synced);
  console.log('Done.')
  console.groupEnd()
}