in-memory-json-persistance.js

const DB_PATH = process.env.DB_PATH || './db.json'
const SAVE_INTERVAL = process.env.SAVE_INTERVAL || 60*1000
const db = require(DB_PATH)
const fs = require('fs')

const saveDB = () => {
  const start = Date.now()
  try {
    fs.writeFile(DB_PATH, JSON.stringify(db), 'utf8', err => {
      if (err) {
        console.error('Unable to save database', err)
        process.exit(1)
      }
      console.log('DB Saved in', ((Date.now() - start) / 1000).toFixed(2), ' seconds')
    })
  } catch (err) {
    console.error('Unable to save database', err)
    process.exit(1)
  }
}

setInterval(saveDB, SAVE_INTERVAL)

process.on('exit', saveDB)

module.exports = db