Memoize functions results using an lru-cache.

Installation

npm i lru-memoizer --save

Intro

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.

Usage

1const memoizer = require("lru-memoizer");
2
3const memoizedGet = memoizer({
4  //defines how to load the resource when
5  //it is not in the cache.
6  load: function (options, callback) {
7    request.get(options, callback);
8  },
9
10  //defines how to create a cache key from the params.
11  hash: function (options) {
12    return options.url + qs.stringify(options.qs);
13  },
14
15  //don't cache in test environment
16  disable: isTestEnv(),
17
18  //all other params for the LRU cache.
19  max: 100,
20  ttl: 1000 * 60,
21});
22
23memoizedGet(
24  {
25    url: "https://google.com",
26    qs: { foo: 123 },
27  },
28  function (err, result, body) {
29    //console.log(body);
30  }
31);

Synchronous lru-memoizer

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.

1const memoizer = require("lru-memoizer");
2const memoizedGet = memoizer.sync({
3  //defines how to load the resource when
4  //it is not in the cache.
5  load: function (params) {
6    return somethingHardToCompute();
7  },
8
9  //defines how to create a cache key from the params.
10  hash: function (params) {
11    return params.foo;
12  },
13
14  //all other params for the LRU cache.
15  max: 100,
16  ttl: 1000 * 60,
17});

Similar modules

This module is very similar to async-cache^(deprecated), the main difference is the hash function.

License

MIT 2016 - José F. Romaniello