JSPM – lru-memoizer@3.0.0

Package Exports

lru-memoizer
lru-memoizer/lib/index.js

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (lru-memoizer) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

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

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);
  }
);

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.

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,
});

Similar modules

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

License

MIT 2016 - José F. Romaniello