Openfinance Cache Library

NOTE: This library is now hosted on github packages at https://github.com/openfinanceio/ts-cache. For the latest updates, please use the package @openfinanceio/ts-cache and point npm to github package repo (github guide).

This is a very small library that implements a simple in-memory cache. It can be segmented (i.e., you can instantiate multiple independent caches with different settings), you can set global and local TTLs, and you can set a max key count to prevent the cache from growing too large.

The interface is very basic:

• To get and cache a value, call Cache::get with a key, a function (optionally async) that returns the value you want to store, and an optional TTL for that key.
• To get a value directly from the cache, call Cache::get without the function or TTL and expect to handle undefined as a return type.
• To clear a specific key from the cache, call Cache::clear(key).
• To clear all keys from the cache, call Cache::clear().

Examples

// Set up a new cache with a global TTL of 600 seconds and at most 10,000 keys
const cache = new Cache({ ttlSec: 600, maxLength: 10000 });

// Get a value from an API through the cache, but give it a shorter TTL
const val = await cache.get(
  "myRemoteVal",
  async () => {
    return await api.getResult();
  }, 
  30
);

// Use the result
if (val === 1) {
  console.log("Remote value is 1");
}

// Get it again for something else
const sameVal = cache.get("myRemoteVal");
if (typeof sameVal !== "undefined") {
  console.log(`Remote val was cached as ${sameVal}`);
}

// Oops! We know something changed that invalidated our cache. Bust it.
cache.clear("myRemoteVal");

// Oh no, lots of uncertainty, what's going on?? Let's just clear the whole cache to be safe....
cache.clear();