🤑 @epic-web/cachified

A simple API to make your app faster.

Cachified allows you to cache values with support for time-to-live (ttl), stale-while-revalidate (swr), cache value validation, batching, and type-safety.

npm install @epic-web/cachified

npm install @epic-web/cachified
# yarn add @epic-web/cachified

import { LRUCache } from 'lru-cache';
import { cachified, CacheEntry, Cache, totalTtl } from '@epic-web/cachified';
/* lru cache is not part of this package but a simple non-persistent cache */
const lruInstance = new LRUCache<string, CacheEntry>({ max: 1000 });
const lru: Cache = {
  set(key, value) {
    const ttl = totalTtl(value?.metadata);
    return lruInstance.set(key, value, {
      ttl: ttl === Infinity ? undefined : ttl,
      start: value?.metadata?.createdTime,
    });
  },
  get(key) {
    return lruInstance.get(key);
  },
  delete(key) {
    return lruInstance.delete(key);
  },
};
function getUserById(userId: number) {
  return cachified({
    key: `user-${userId}`,
    cache: lru,
    async getFreshValue() {
      /* Normally we want to either use a type-safe API or `checkValue` but
         to keep this example simple we work with `any` */
      const response = await fetch(
        `https://jsonplaceholder.typicode.com/users/${userId}`,
      );
      return response.json();
    },
    /* 5 minutes until cache gets invalid
     * Optional, defaults to Infinity */
    ttl: 300_000,
  });
}
// Let's get through some calls of `getUserById`:
console.log(await getUserById(1));
// > logs the user with ID 1
// Cache was empty, `getFreshValue` got invoked and fetched the user-data that
// is now cached for 5 minutes
// 2 minutes later
console.log(await getUserById(1));
// > logs the exact same user-data
// Cache was filled an valid. `getFreshValue` was not invoked
// 10 minutes later
console.log(await getUserById(1));
// > logs the user with ID 1 that might have updated fields
// Cache timed out, `getFreshValue` got invoked to fetch a fresh copy of the user
// that now replaces current cache entry and is cached for 5 minutes