Memoize functions results using an lru-cache.
npm i lru-memoizer --save
This module uses an lru-cache internally to cache the results of an async function.
The load function can have N parameters and the last one must be a callback. The callback should be an errback (first parameter is err).
The hash function purpose is generate a custom hash for storing results. It has all the arguments applied to it minus the callback, and must return a synchronous string.
The disable function allows you to conditionally disable the use of the cache. Useful for test environments.
The freeze option (defaults to false) allows you to deep-freeze the result of the async function.
The clone option (defaults to false) allows you to deep-clone the result every time is returned from the cache.
const memoizer = require("lru-memoizer");
const memoizedGet = memoizer({
//defines how to load the resource when
//it is not in the cache.
load: function (options, callback) {
request.get(options, callback);
},
//defines how to create a cache key from the params.
hash: function (options) {
return options.url + qs.stringify(options.qs);
},
//don't cache in test environment
disable: isTestEnv(),
//all other params for the LRU cache.
max: 100,
ttl: 1000 * 60,
});
memoizedGet(
{
url: "https://google.com",
qs: { foo: 123 },
},
function (err, result, body) {
//console.log(body);
}
);Use memoizer.sync to cache things that are slow to calculate, methods returning promises, or only if you don't want to use a callback and want it synchronous.
const memoizer = require("lru-memoizer");
const memoizedGet = memoizer.sync({
//defines how to load the resource when
//it is not in the cache.
load: function (params) {
return somethingHardToCompute();
},
//defines how to create a cache key from the params.
hash: function (params) {
return params.foo;
},
//all other params for the LRU cache.
max: 100,
ttl: 1000 * 60,
});This module is very similar to async-cache(deprecated), the main difference is the hash function.
MIT 2016 - José F. Romaniello