lru_cache_quickstart_with_ttl_size_and_fetch.ts

1import { LRUCache } from 'lru-cache'
2
3const options: LRUCache.Options<string, string, unknown> = {
4  max: 500,
5
6  // for caches that should be limited by size of numbers, rather than number of items.
7  maxSize: 5000,
8  sizeCalculation: (value, key) => {
9    return value.length + key.length
10  },
11
12  // how long to live in ms
13  ttl: 1000 * 60 * 5,
14
15  // return stale items before removing from cache?
16  allowStale: false,
17
18  updateAgeOnGet: false,
19  updateAgeOnHas: false,
20
21  // async method to use for cache.fetch(), for weeding out double-gets
22  fetchMethod: async (
23    key: string,
24    staleValue: string | undefined,
25    { options, signal, context }
26  ) => {
27    return 'value'
28  },
29}
30
31const cache = new LRUCache<string, string>(options)
32
33cache.set('key', 'value')
34const value = cache.get('key') // "value"
35
36cache.has('key') // true
37cache.delete('key')
38cache.get('key') // undefined