remember-promise
A simple utility to remember promises that were made! It is greatly inspired by the p-memoize utility but with additional built-in features and changes such as:
- ttl expiry
- stale-while-revalidate behavior
- ability to ignore results from being cached
- optimal probabilistic cache stampede prevention
- zero dependencies + tiny bundle size + commonjs, deno (via esm.sh) and browser support!
Installation
yarn:
yarn add remember-promise
npm:
npm install remember-promise
pnpm:
pnpm install remember-promise
Usage
import { rememberPromise } from 'remember-promise';
const getRedditFeed = rememberPromise(
subreddit =>
fetch(`https://www.reddit.com/r/${subreddit}.json`).then(res => res.json()),
{
ttl: 300_000, // 5 minutes before the result must be revalidated again
/* see below for a full list of available options */
}
);
const firstResult = await getRedditFeed('all');
const secondResult = await getRedditFeed('all'); // this call is cached
Options
| Name | Description |
|---|---|
ttl |
Configures how long in milliseconds the cached result should be used before needing to be revalidated. Additionally, setting this value to a negative number will disable caching. NOTE: the actual revalidation of the cached result is done slightly before expiry by default. This can be adjusted using the xfetchBeta option. By default this is undefined so the cached result will be used indefinitely. |
allowStale |
This enables stale-while-revalidate behavior where an expired result can still be used while waiting for it to be updated in the background asynchronously. By default this is set to true so the behavior is enabled. |
cache |
This is where cached results will be stored. It can be anything you want such as lru-cache or a redis backed cache as long as it implements a get and set method defined in the AsyncMapLike type. By default this is a new instance of Map. |
getCacheKey |
Identical behavior to the cacheKey option in p-memoize except that it's allowed to return a promise. It should return what the cache key is based on the parameters of the given function. By default this will serialize all arguments using JSON.stringify. |
onCacheUpdateError |
Use this to catch errors when attempting to update the cache or if shouldIgnoreResult throws an error. By default this is undefined which means any errors will be rethrown as an unhandled promise rejection. |
shouldIgnoreResult |
Determines whether the returned result should be added to the cache. By default this is undefined which means it will always use the returned result for caching. |
xfetchBeta |
This is the beta value used in optimal probabilistic cache stampede prevention where values more than 1 favors earlier revalidation while values less than 1 favors later revalidation. By default this is set to 1 so the revalidation of a cached result will happen at a random time slightly before expiry. If you wish to opt-out of this behavior, then set this value to 0. |
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