NodeJS Cache

README.md

How to Use

The interface was greatly inspired by Rails' low level caching implementation.

import { MemoryStore, Cache } from './cache'

const store = new MemoryStore({ ttl: 30 * 1000, max: 10 })
const cache = new Cache(store)

cache.js

import MemoryStore from './memory-store'

class Cache {
  constructor(store = new MemoryStore()) {
    this.store = store
  }

  async fetch(key, fetchFunction) {
    let value = await this.store.fetch(key)
    if (!value) {
      value = await fetchFunction()
      this.store.write(key, value)
    }
    return value
  }
}

export default Cache

index.js

export { default as Cache } from './cache'
export { default as MemoryStore } from './memory-store'

memory-store.js

import { LRUCache } from 'lru-cache'

class MemoryStore {
  constructor(options = {}) {
    this.lruCache = this.createCache(options)
  }

  createOptions(options) {
    return {
      // how long to live in ms (defaults to 5m)
      ttl: 5 * 60 * 1000,

      // max number of items to store (defaults to 500)
      max: 500,

      ...options,
    }
  }

  createCache(options) {
    const opts = this.createOptions(options)
    return new LRUCache(opts)
  }

  async fetch(key) {
    return this.lruCache.get(key)
  }

  async write(key, value) {
    return this.lruCache.set(key, value)
  }
}

export default MemoryStore