level-ttl

const level = require('level')
const sublevel = require('level-sublevel')
const ttl = require('level-ttl')
const Trigger = require('level-trigger')

const db = ttl(level('./db'), {checkFrequency: 50})

db.on('del', key => {
	console.log('KEY DELETED:', key)
})

db.put('foo', 'bar', {ttl: 1000}, (err) => {
	if (err) {
		return console.log('ERR:', err)
	}
	console.log('done')
})

setTimeout(function () { //before key expires
	db.get('foo', function (err, value) {
		console.log(err && err.notFound) // -> null
		console.log(value) // -> 'wazzup'
	})
}, 900)

setTimeout(function () { //after key expires
	db.get('foo', function (err, value) {
		console.log(err && err.notFound) // -> true
		console.log(value) // -> undefined
	})
}, 3000)