Package Exports

micro-memoize

Readme

micro-memoize

A tiny, crazy fast memoization library for the 95% use-case

micro-memoize

Summary

As the author of moize, I created a consistently fast memoization library, but moize has a lot of features to satisfy a large number of edge cases. micro-memoize is a simpler approach, focusing on the core feature set with a much smaller footprint (~1.37kB minified+gzipped). Stripping out these edge cases also allows micro-memoize to be faster across the board than moize.

Importing

ESM:

import { memoize } from 'micro-memoize';

CommonJS:

const { memoize } = require('micro-memoize');

Usage

const assembleToObject = (one: string, two: string) => ({ one, two });

const memoized = memoize(assembleToObject);

console.log(memoized('one', 'two')); // {one: 'one', two: 'two'}
console.log(memoized('one', 'two')); // pulled from cache, {one: 'one', two: 'two'}

Composition

Starting in 4.0.0, you can compose memoized functions if you want to have multiple types of memoized versions based on different options.

const simple = memoized(fn); // { maxSize: 1 }
const upToFive = memoized(simple, { maxSize: 5 }); // { maxSize: 5 }
const withCustomEquals = memoized(upToFive, { isEqual: deepEqual }); // { maxSize: 5, isEqual: deepEqual }

NOTE: The original function is the function used in the composition, the composition only applies to the options. In the example above, upToFive does not call simple, it calls fn.

Options

async

boolean, defaults to false

Identifies the value returned from the method as a Promise, which will result in one of two possible scenarios:

If the promise is resolved, it will fire the onCacheHit and onCacheChange options
If the promise is rejected, it will trigger auto-removal from cache

const fn = async (one: string, two: string) => {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      reject(new Error(JSON.stringify({ one, two })));
    }, 500);
  });
};

const memoized = memoize(fn, { isPromise: true });

memoized('one', 'two');

console.log(memoized.cache.snapshot.keys); // [['one', 'two']]
console.log(memoized.cache.snapshot.values); // [Promise]

setTimeout(() => {
  console.log(memoized.cache.snapshot.keys); // []
  console.log(memoized.cache.snapshot.values); // []
}, 1000);

NOTE: If you don't want rejections to auto-remove the entry from cache, set isPromise to false (or simply do not set it), but be aware this will also remove the cache listeners that fire on successful resolution.

isKeyEqual

function(object1: any[], object2: any[]): boolean

Custom method to compare equality of keys, determining whether to pull from cache or not, by comparing the entire key.

Common use-cases:

Comparing the shape of the key
Matching on values regardless of order
Serialization of arguments

import { deepEqual } from 'fast-equals';

type ContrivedObject = { foo: string; bar: number };

const deepObject = (object: ContrivedObject) => ({
  foo: object.foo,
  bar: object.bar,
});

const memoizedShape = memoize(deepObject, {
  // receives the full key in cache and the full key of the most recent call
  isKeyEqual(key1, key2) {
    const object1 = key1[0];
    const object2 = key2[0];

    return (
      object1.hasOwnProperty('foo') &&
      object2.hasOwnProperty('foo') &&
      object1.bar === object2.bar
    );
  },
});

console.log(
  memoizedShape({
    foo: 'foo',
    bar: 123,
    baz: 'baz',
  }),
); // {foo: {deep: 'foo'}, bar: {deep: 'bar'}}

console.log(
  memoizedShape({
    foo: 'not foo',
    bar: 123,
    baz: 'baz',
  }),
); // pulled from cache

isKeyItemEqual

function(object1: any, object2: any): boolean, defaults to Object.is

Custom method to compare equality of keys, determining whether to pull from cache or not, by comparing each argument in order.

Common use-cases:

Deep equality comparison
Limiting the arguments compared

import { deepEqual } from 'fast-equals';

type ContrivedObject = {
  deep: string;
};

const deepObject = (object: {
  foo: ContrivedObject;
  bar: ContrivedObject;
}) => ({
  foo: object.foo,
  bar: object.bar,
});

const memoizedDeepObject = memoize(deepObject, { isKeyItemEqual: deepEqual });

console.log(
  memoizedDeepObject({
    foo: {
      deep: 'foo',
    },
    bar: {
      deep: 'bar',
    },
    baz: {
      deep: 'baz',
    },
  }),
); // {foo: {deep: 'foo'}, bar: {deep: 'bar'}}

console.log(
  memoizedDeepObject({
    foo: {
      deep: 'foo',
    },
    bar: {
      deep: 'bar',
    },
    baz: {
      deep: 'baz',
    },
  }),
); // pulled from cache

NOTE: The default method tests for SameValueZero equality, which is summarized as strictly equal while also considering NaN equal to NaN.

maxSize

number, defaults to 1

The number of values to store in cache, based on a Least Recently Used basis. This operates the same as maxSize on moize.

const manyPossibleArgs = (one: string, two: string) => [one, two];

const memoized = memoize(manyPossibleArgs, { maxSize: 3 });

console.log(memoized('one', 'two')); // ['one', 'two']
console.log(memoized('two', 'three')); // ['two', 'three']
console.log(memoized('three', 'four')); // ['three', 'four']

console.log(memoized('one', 'two')); // pulled from cache
console.log(memoized('two', 'three')); // pulled from cache
console.log(memoized('three', 'four')); // pulled from cache

console.log(memoized('four', 'five')); // ['four', 'five'], drops ['one', 'two'] from cache

transformKey

function(Array<any>): any

A method that allows you transform the key that is used for caching, if you want to use something other than the pure arguments.

const ignoreFunctionArgs = (one: string, two: () => {}) => [one, two];

const memoized = memoize(ignoreFunctionArgs, {
  transformKey: (args) => [JSON.stringify(args[0])],
});

console.log(memoized('one', () => {})); // ['one', () => {}]
console.log(memoized('one', () => {})); // pulled from cache, ['one', () => {}]

If your transformed keys require something other than SameValueZero equality, you can combine transformKey with isEqual for completely custom key creation and comparison.

const ignoreFunctionArg = (one: string, two: () => void) => [one, two];

const memoized = memoize(ignoreFunctionArg, {
  isMatchingKey: (key1, key2) => key1[0] === key2[0],
  // Cache based on the serialized first parameter
  transformKey: (args) => [JSON.stringify(args[0])],
});

console.log(memoized('one', () => {})); // ['one', () => {}]
console.log(memoized('one', () => {})); // pulled from cache, ['one', () => {}]

Additional properties

memoized.cache

Object

The cache object that is used internally. The shape of this structure:

{
  keys: any[][], // available as MicroMemoize.Key[]
  values: any[] // available as MicroMemoize.Value[]
}

The exposure of this object is to allow for manual manipulation of keys/values (injection, removal, expiration, etc).

const method = (one: string, two: string) => ({ one, two });

const memoized = memoize(method);

memoized.cache.keys.push(['one', 'two']);
memoized.cache.values.push('cached');

console.log(memoized('one', 'two')); // 'cached'

NOTE: moize offers a variety of convenience methods for this manual cache manipulation, and while micro-memoize allows all the same capabilities by exposing the cache, it does not provide any convenience methods.

memoized.cache.on

Add listeners to specific cache events, in case you want to perform side-effects.

add

Executes whenever the cache is added to.

const fn = (one: string, two: string) => [one, two];

const memoized = memoize(fn, { maxSize: 2 });

memoized.cache.on('add', (event) => {
  console.log('cache has been added to: ', JSON.stringify(event));
});

memoized('foo', 'bar'); // cache has been added to
memoized('foo', 'bar');
memoized('foo', 'bar');
memoized('bar', 'foo'); // cache has been added to
memoized('bar', 'foo');
memoized('bar', 'foo');
memoized('foo', 'bar');
memoized('foo', 'bar');
memoized('foo', 'bar');

delete

Executes whenever the cache has an entry removed.

const fn = (one: string, two: string) => [one, two];

const memoized = memoize(fn);

memoized.cache.on('delete', (event) => {
  console.log('cache has changed: ', JSON.stringify(event));
});

memoized('foo', 'bar');
memoized('foo', 'bar');
memoized('foo', 'bar');
memoized('bar', 'foo'); // cache has changed
memoized('bar', 'foo');
memoized('bar', 'foo');
memoized('foo', 'bar'); // cache has changed
memoized('foo', 'bar');
memoized('foo', 'bar');

NOTE: This method is not executed when the cache is manually manipulated, only when changed via calling the memoized method. When the execution of other cache listeners (onCacheAdd, onCacheHit) is applicable, this method will execute after those methods.

hit

Executes whenever the cache is hit, whether the order is updated or not.

const fn = (one: string, two: string) => [one, two];

const memoized = memoize(fn, { maxSize: 2 });

memoized.cache.on('update', (event) => {
  console.log('cache entry found: ', JSON.stringify(event));
});

memoized('foo', 'bar');
memoized('foo', 'bar'); // cache entry was found
memoized('foo', 'bar'); // cache entry was found
memoized('bar', 'foo');
memoized('bar', 'foo'); // cache entry was found
memoized('bar', 'foo'); // cache entry was found
memoized('foo', 'bar'); // cache entry was found
memoized('foo', 'bar'); // cache entry was found
memoized('foo', 'bar'); // cache entry was found

update

Executes whenever the cache has the order of entries change due to an older entry being accessed more recently.

const fn = (one: string, two: string) => [one, two];

const memoized = memoize(fn, { maxSize: 2 });

memoized.cache.on('update', (event) => {
  console.log('cache has changed: ', JSON.stringify(event));
});

memoized('foo', 'bar');
memoized('bar', 'foo'); // cache has changed
memoized('bar', 'foo');
memoized('bar', 'foo');
memoized('foo', 'bar'); // cache has changed
memoized('foo', 'bar');
memoized('foo', 'bar');

NOTE: This method is not executed when the cache is manually manipulated, only when changed via calling the memoized method.

memoized.cache.snapshot

Object

Provide a persistent snapshot of the values at that time. This is useful when tracking the cache changes over time, as the cache object is mutated internally for performance reasons.

memoized.fn

function

The original function passed to be memoized.

memoized.isMemoized

boolean

Hard-coded to true when the function is memoized. This is useful for introspection, to identify if a method has been memoized or not.

memoized.options

Object

The options passed when creating the memoized method.

Benchmarks

All values provided are the number of operations per second (ops/sec) calculated by the Benchmark suite. Note that underscore, lodash, and ramda do not support mulitple-parameter memoization (which is where micro-memoize really shines), so they are not included in those benchmarks.

Benchmarks was performed on an i9 16-core Linux laptop with 64GB of memory using NodeJS version 24.11.0. The default configuration of each library was tested with a fibonacci calculation based on the following parameters:

Single primitive = 35
Single array = [35]
Single object = { number: 35 }
Multiple primitives = 35, true
Multiple arrays = [35], [true]
Multiple objects = { number: 35 }, { isComplete: true }

NOTE: Not all libraries tested support multiple parameters out of the box, but support the ability to pass a custom resolver. Because these often need to resolve to a string value, a common suggestion is to just JSON.stringify the arguments, so that is what is used when needed.

Single primitive parameter

┌───────────────┬─────────────────┐
│ Name          │ Ops / sec       │
├───────────────┼─────────────────┤
│ micro-memoize │ 20835481.677781 │
├───────────────┼─────────────────┤
│ fast-memoize  │ 20232300.17637  │
├───────────────┼─────────────────┤
│ mem           │ 19994011.13034  │
├───────────────┼─────────────────┤
│ lru-memoize   │ 19932052.414257 │
├───────────────┼─────────────────┤
│ lodash        │ 19767301.515183 │
├───────────────┼─────────────────┤
│ ramda         │ 16750286.526908 │
├───────────────┼─────────────────┤
│ addy osmani   │ 15997647.118581 │
├───────────────┼─────────────────┤
│ memoizee      │ 14940710.869491 │
├───────────────┼─────────────────┤
│ underscore    │ 14748024.063232 │
├───────────────┼─────────────────┤
│ memoizerific  │ 9767077.924623  │
└───────────────┴─────────────────┘
Fastest was "micro-memoize".

Single array parameter

┌───────────────┬─────────────────┐
│ Name          │ Ops / sec       │
├───────────────┼─────────────────┤
│ micro-memoize │ 18357195.833636 │
├───────────────┼─────────────────┤
│ lodash        │ 17055087.842295 │
├───────────────┼─────────────────┤
│ lru-memoize   │ 15833396.741078 │
├───────────────┼─────────────────┤
│ memoizee      │ 12340803.82622  │
├───────────────┼─────────────────┤
│ memoizerific  │ 8794963.869935  │
├───────────────┼─────────────────┤
│ mem           │ 5293693.748716  │
├───────────────┼─────────────────┤
│ ramda         │ 4976738.640437  │
├───────────────┼─────────────────┤
│ underscore    │ 4792112.350974  │
├───────────────┼─────────────────┤
│ addy osmani   │ 4170246.035472  │
├───────────────┼─────────────────┤
│ fast-memoize  │ 2352637.727387  │
└───────────────┴─────────────────┘
Fastest was "micro-memoize".

Single object parameter

┌───────────────┬─────────────────┐
│ Name          │ Ops / sec       │
├───────────────┼─────────────────┤
│ micro-memoize │ 18658205.025206 │
├───────────────┼─────────────────┤
│ lodash        │ 16750836.138366 │
├───────────────┼─────────────────┤
│ lru-memoize   │ 16578406.184478 │
├───────────────┼─────────────────┤
│ memoizee      │ 12266601.972724 │
├───────────────┼─────────────────┤
│ memoizerific  │ 8852707.137848  │
├───────────────┼─────────────────┤
│ mem           │ 4201688.219408  │
├───────────────┼─────────────────┤
│ ramda         │ 3905113.798295  │
├───────────────┼─────────────────┤
│ underscore    │ 3778464.34052   │
├───────────────┼─────────────────┤
│ addy osmani   │ 3099906.414763  │
├───────────────┼─────────────────┤
│ fast-memoize  │ 2106804.868118  │
└───────────────┴─────────────────┘
Fastest was "micro-memoize".

Multiple primitive parameters

┌───────────────┬─────────────────┐
│ Name          │ Ops / sec       │
├───────────────┼─────────────────┤
│ micro-memoize │ 17204027.880701 │
├───────────────┼─────────────────┤
│ lru-memoize   │ 15633853.842073 │
├───────────────┼─────────────────┤
│ memoizee      │ 8841419.676384  │
├───────────────┼─────────────────┤
│ memoizerific  │ 6828412.055858  │
├───────────────┼─────────────────┤
│ addy osmani   │ 5524312.45204   │
├───────────────┼─────────────────┤
│ mem           │ 5183756.056456  │
├───────────────┼─────────────────┤
│ ramda         │ 4105423.769628  │
├───────────────┼─────────────────┤
│ underscore    │ 3949386.432982  │
├───────────────┼─────────────────┤
│ lodash        │ 3810555.610425  │
├───────────────┼─────────────────┤
│ fast-memoize  │ 1981969.342187  │
└───────────────┴─────────────────┘
Fastest was "micro-memoize".

Multiple array parameters

┌───────────────┬─────────────────┐
│ Name          │ Ops / sec       │
├───────────────┼─────────────────┤
│ micro-memoize │ 17560684.286925 │
├───────────────┼─────────────────┤
│ lru-memoize   │ 15983007.720596 │
├───────────────┼─────────────────┤
│ memoizee      │ 8959060.057045  │
├───────────────┼─────────────────┤
│ memoizerific  │ 7458758.225714  │
├───────────────┼─────────────────┤
│ mem           │ 4356654.09796   │
├───────────────┼─────────────────┤
│ ramda         │ 3571942.088031  │
├───────────────┼─────────────────┤
│ underscore    │ 3457583.224377  │
├───────────────┼─────────────────┤
│ lodash        │ 3347522.058684  │
├───────────────┼─────────────────┤
│ addy osmani   │ 2607779.086579  │
├───────────────┼─────────────────┤
│ fast-memoize  │ 1743301.139086  │
└───────────────┴─────────────────┘
Fastest was "micro-memoize".

Multiple object parameters

┌───────────────┬─────────────────┐
│ Name          │ Ops / sec       │
├───────────────┼─────────────────┤
│ micro-memoize │ 17921163.841926 │
├───────────────┼─────────────────┤
│ lru-memoize   │ 15838957.230428 │
├───────────────┼─────────────────┤
│ memoizee      │ 8736014.364781  │
├───────────────┼─────────────────┤
│ memoizerific  │ 7476373.562525  │
├───────────────┼─────────────────┤
│ mem           │ 3081651.284228  │
├───────────────┼─────────────────┤
│ ramda         │ 2636822.103479  │
├───────────────┼─────────────────┤
│ underscore    │ 2564488.076442  │
├───────────────┼─────────────────┤
│ lodash        │ 2506526.814622  │
├───────────────┼─────────────────┤
│ addy osmani   │ 2075173.560066  │
├───────────────┼─────────────────┤
│ fast-memoize  │ 1490035.752335  │
└───────────────┴─────────────────┘
Fastest was "micro-memoize".

Browser support

Chrome 47+
Firefox 15+
Edge 12+
Opera 34+
Safari 10+

Node support

Development

Standard stuff, clone the repo and npm install dependencies. The npm scripts available:

benchmark => run benchmarks against well-known alternative packages
build => run rollup to build the dist files
build:cjs => run rollup to build the dist files specific to CJS requires
build:esm => run rollup to build the dist files specific to ESM imports
build:min => run rollup to build the dist files specific to pre-minified files
build:umd => run rollup to build the dist files specific to legacy environments, such as Node 10
clean: remove dist folder
clean:cjs: remove dist/cjs folder
clean:esm: remove dist/esm folder
clean:min: remove dist/min folder
clean:umd: remove dist/umd folder
dev => run webpack dev server to run example app (playground!)
dist => runs build and build-minified
lint => run ESLint against all files in the src folder
release => runs the release process, which publishes the latest version of the package
release:beta => runs the beta release process, which publishes the next beta version of the package
release:scripts => run the precursor tasks as part of the release process
test => run unit tests
test:coverage => run test but with coverage
test:watch => run test but with persistent watcher
typecheck => run tsc to verify types are valid

JSPM

micro-memoize

Package Exports

Readme

micro-memoize

Table of contents

Summary

Importing

Usage

Composition

Options

async

isKeyEqual

isKeyItemEqual

maxSize

transformKey

Additional properties

memoized.cache

memoized.cache.on

add

delete

hit

update

memoized.cache.snapshot

memoized.fn

memoized.isMemoized

memoized.options

Benchmarks

Single primitive parameter

Single array parameter

Single object parameter

Multiple primitive parameters

Multiple array parameters

Multiple object parameters

Browser support

Node support

Development