An overly-simplified cache library for node v4+

cache.js

'use strict';

const lowdb = require('lowdb');
const storage = require('lowdb/file-sync');
const db = lowdb(`${ __dirname }/db.json`, { storage });

const COLLECTION_ID = 'cache';
const ONE_HOUR = 3600;

const isValidCacheKey = (key, ttl) =>
 	Math.floor((Date.now() - key.created) / 1000) <= ttl;

class CacheKey {
	constructor(key, value) {
		this.created = Date.now();
		Object.assign(this, { key, value });
	}
}

class Cache {
	constructor(opts) {
		this.stdTTL = opts.stdTTL || 600;
		this.db = db(COLLECTION_ID);
	}

	get(key) {
		const cached = this.db.find({ key });

		return cached && isValidCacheKey(cached, this.stdTTL)
			? cached.value
			: this.invalidate(key);
	}

	set(key, value) {
		this.db.push(new CacheKey(key, value));
	}

	invalidate(key) {
		this.db.remove({ key });
	}
}

module.exports = new Cache({ stdTTL: ONE_HOUR });