moize

moize is a consistently blazing fast memoization library for JavaScript. It handles multiple parameters (including default values) without any additional configuration, and offers a large number of options to satisfy any number of potential use-cases.

• Importing
  • ESM in browsers
  • ESM in NodeJS
  • CommonJS
• Usage
• Configuration options
  • isDeepEqual
  • isPromise
  • isReact
  • isSerialized
  • isShallowEqual
  • matchesArg
  • matchesKey
  • maxAge
  • maxArgs
  • maxSize
  • onCacheAdd
  • onCacheChange
  • onCacheHit
  • onExpire
  • profileName
  • serializer
  • transformArgs
  • updateCacheForKey
  • updateExpire
• Usage with shortcut methods
  • moize.deep
  • moize.infinite
  • moize.matchesArg
  • moize.matchesKey
  • moize.maxAge
  • moize.maxArgs
  • moize.maxSize
  • moize.profile
  • moize.promise
  • moize.react
  • moize.serialize
  • moize.serializeWith
  • moize.shallow
  • moize.transformArgs
  • moize.updateCacheForKey
• useMoize hook
• Composition
• Collecting statistics
  • Stats methods
  • clearStats
  • collectStats
  • getStats([profileName])
• Introspection
  • isCollectingStats
  • isMoized
• Direct cache manipulation
  • cache
  • cacheSnapshot
  • add(key, value)
  • clear()
  • get(key)
  • getStats()
  • has(key)
  • keys()
  • remove(key)
  • update(key, value)
  • values()
• Benchmarks
• Filesize
• Browser support
• Development

$ npm i moize --save

Importing

ESM in browsers

import moize from 'moize';

ESM in NodeJS

import moize from 'moize/mjs/index.mjs';

CommonJS

const moize = require('moize');

Usage

import moize from 'moize';

const method = (a: number, b: number) => a + b;

const memoized = moize(method);

memoized(2, 4); // 6
memoized(2, 4); // 6, pulled from cache

All parameter types are supported, including circular objects, functions, etc. There are also a number of shortcut methods to memoize for unique use-cases.

Configuration options

moize optionally accepts an object of options as either the second parameter or as the first step in a curried function:

// inline
moize(fn, options);

// curried
moize(options)(fn);

The full shape of these options:

type Options = {
    // is the cache based on deep equality of each key argument
    isDeepEqual: boolean;
    // is the result a promise
    isPromise: boolean;
    // is the result a React component
    isReact: boolean;
    // should the parameters be serialized instead of directly referenced
    isSerialized: boolean;
    // is the cache based on shallow equality of each key argument
    isShallowEqual: boolean;
    // custom method to compare equality between two key arguments
    matchesArg: (cachedKeyArg: any, keyArg: any) => boolean;
    // custom method to compare equality across all key arguments
    matchesKey: (cachedKey: any[], key: any[]) => boolean;
    // amount of time in milliseconds before the cache will expire
    maxAge: number;
    // maximum number of arguments passed to use as key for caching
    maxArgs: number;
    // maximum size of cache for this method
    maxSize: number;
    // method fired when a new entry is added to cache
    onCacheAdd: (
        cache: moize.Cache,
        options: moize.Options,
        moized: (...args: any[]) => any
    ) => void;
    // method fire when either a new entry is added to cache or the LRU ordering of the cache has changed
    onCacheChange: (
        cache: moize.Cache,
        options: moize.Options,
        moized: (...args: any[]) => any
    ) => void;
    // method fired when an existing entry in cache is used
    onCacheHit: (
        cache: moize.Cache,
        options: moize.Options,
        moized: (...args: any[]) => any
    ) => void;
    // method to fire when a cache entry expires (in combination with maxAge)
    onExpire: (key: any[]) => void;
    // the unique identifier to give the memoized method when collecting statistics
    profileName: string;
    // method to serialize the arguments to build a unique cache key
    serializer: (key: any[]) => string;
    // method to transform the args into a custom format for key storage in cache
    transformArgs: (key: any[]) => any[];
    // should the cache entry be refreshed by calling the underlying function with the same parameters and
    // updating the value stored in cache to be the new result
    updateCacheForKey: (key: any[]) => boolean;
    // should the cache entry's expiration be refreshed when the cache entry is hit (in combination with maxAge)
    updateExpire: boolean;
};

All default values can be found here.

isDeepEqual

defaults to false

Should deep equality be used to compare cache each key argument.

type Arg = {
    one: {
        nested: string;
    };
    two: string;
};

const fn = ({ one, two }: Arg) => [one, two];

const memoized = moize(fn, { isDeepEqual: true });

memoized({ one: { nested: 'one' }, two: 'two' });
memoized({ one: { nested: 'one' }, two: 'two' }); // pulls from cache

This is also available via the shortcut method of moize.deep

const memoized = moize.deep(fn);

isPromise

defaults to false

Is the computed value in the function a Promise.

const fn = async (item: Promise<string>) => await item;

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

This is also available via the shortcut method of moize.promise.

const memoized = -moize.promise(fn);

The Promise itself will be stored in cache, so that cached returns will always maintain the Promise contract. For common usage reasons, if the Promise is rejected, the cache entry will be deleted.

isReact

defaults to false

Is the function passed a stateless functional React component.

type Props = {
    one: string;
    two: number;
};

const Component = ({ one, two }: Props) => (
    <div>
        {one}: {two}
    </div>
);

const MemoizedFoo = moize(Component, { isReact: true });

This is also available via the shortcut method of moize.react.

const MemoizedFoo = moize.react(Component);

The method will do a shallow equal comparison of both props and legacy context of the component based on strict equality. If you want to do a deep equals comparison, set isDeepEqual to true.

NOTE: This will memoize on each instance of the component passed, which is equivalent to PureComponent or React.memo. If you want to memoize on all instances (which is how this option worked prior to version 6), use the following options:

const memoized = moize(Component, { isShallowEqual: true, maxArgs: 2 });

isSerialized

defaults to false

Serializes the parameters passed into a string and uses this as the key for cache comparison.

const fn = (mutableObject: { one: Record<string, any> }) =>
    mutableObject.property;

const memoized = moize(fn, { isSerialized: true });

This is also available via the shortcut method of moize.serialize.

const memoized = moize.serialize(fn);

If serialize is combined with either maxArgs or transformArgs, the following order is used:

1. limit by maxArgs (if applicable)
2. transform by transformArgs (if applicable)
3. serialize by serializer

NOTE: This is much slower than the default key storage, and usually the same requirements can be meet with isDeepEqual, so use at your discretion.

isShallowEqual

defaults to false

Should shallow equality be used to compare cache each key argument.

type Arg = {
    one: string;
    two: string;
};

const fn = ({ one, two }: Arg) => [one, two];

const memoized = moize(fn, { isShallowEqual: true });

memoized({ one: 'one', two: 'two' });
memoized({ one: 'one', two: 'two' }); // pulls from cache

This is also available via the shortcut method of moize.shallow

const memoized = moize.shallow(fn);

matchesArg

defaults to SameValueZero equality

Custom method used to compare equality of keys for cache purposes by comparing each argument.

type Arg = {
    one: string;
    two: string;
};

const fn = ({ one, two }: Arg) => [one, two];

const hasOneProperty = (cacheKeyArg: Arg, keyArg: Arg) =>
    Object.keys(cacheKeyArg).length === 1 && Object.keys(keyArg).length === 1;

const memoized = moize(fn, { matchesArg: hasOneProperty });

memoized({ one: 'two' };
memoized({ two: 'three' }); // pulls from cache

This is also available via the shortcut method of moize.matchesArg

const memoized = moize.matchesArg(hasOneProperty)(fn);

NOTE: This comparison is used iteratively on each argument, rather than comparing the two keys as a whole. If you want to compare the key as a whole, you should use matchesKey.

matchesKey

Custom method used to compare equality of keys for cache purposes by comparing the entire key.

type Arg = {
    one: string;
    two: string;
};

const fn = ({ one, two }: Arg) => [one, two];

const isFooEqualAndHasBar = (cacheKey: [Arg], key: [Arg]) =>
    cacheKey[0].one === key[0].one &&
    cacheKey[1].hasOwnProperty('two') &&
    key[1].hasOwnProperty('two');

const memoized = moize(fn, { matchesKey: isFooEqualAndHasBar });

memoized({ one: 'two' }, { two: null });
memoized({ one: 'two' }, { two: 'three' }); // pulls from cache

This is also available via the shortcut method of moize.matchesKey

const memoized = moize.matchesKey(isFooEqualAndHasBar)(fn);

NOTE: This comparison uses the two keys as a whole, which is usually less performant than the matchArg comparison used iteratively on each argument. Generally speaking you should use the matchArg option for equality comparison.

maxAge

The maximum amount of time in milliseconds that you want a computed value to be stored in cache for this method.

const fn = (item: Record<string, any>) => item;

const MAX_AGE = 1000 * 60 * 5; // five minutes;

const memoized = moize(fn, { maxAge: MAX_AGE });

This is also available via the shortcut method of moize.maxAge.

const memoized = moize.maxAge(MAX_AGE)(fn);

TIP: A common usage of this is in tandem with isPromise for AJAX calls, and in that scenario the expected behavior is usually to have the maxAge countdown begin upon resolution of the promise. If this is your intended use case, you should also apply the updateExpire option.

maxArgs

The maximum number of arguments (starting from the first) used in creating the key for the cache.

const fn = (item1: string, item2: string, item3: string) =>
    item1 + item2 + item3;

const memoized = moize(fn, { maxArgs: 2 });

memoize('one', 'two', 'three');
memoize('one', 'two', 'four'); // pulls from cache, as the first two args are the same

This is also available via the shortcut method of moize.maxArgs.

const memoized = moize.maxArgs(2)(fn);

If maxArgs is combined with either serialize or transformArgs, the following order is used:

1. limit by maxArgs
2. transform by transformArgs (if applicable)
3. serialize by serializer (if applicable)

maxSize

defaults to 1

The maximum number of values you want stored in cache for this method. Clearance of the cache once the maxSize is reached is on a Least Recently Used basis.

const fn = (item: string) => item;

const memoized = moize(fn, { maxSize: 5 });

This is also available via the shortcut method of moize.maxSize.

const memoized = moize.maxSize(5)(fn);

onCacheAdd

Method to fire when an item has been added to cache. Receives the cache, options, and memoized function as a parameters.

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

const logCacheKeys = (
    cache: Cache,
    options: Options,
    moized: Moized<typeof fn>
) => console.log(cache.keys);

const moized = moize(fn, { maxSize: 2, onCacheAdd: logCacheKeys });

moized('one', 'two'); // [["one","two"]]
moized('one', 'two');
moized('two', 'one'); // [["two","one"], ["one","two"]]
moized('one', 'two');

NOTE: When combined with onCacheChange, this method will always fire first.

onCacheChange

Method to fire when an item has been either added to cache, or existing cache was reordered based on a cache hit. Receives the cache, options, and memoized function as a parameters.

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

const logCacheKeys = (
    cache: Cache,
    options: Options,
    moized: Moized<typeof fn>
) => console.log(cache.keys);

const moized = moize(fn, { maxSize: 2, onCacheChange: logCacheKeys });

moized('one', 'two'); // [["one","two"]]
moized('one', 'two');
moized('two', 'one'); // [["two","one"], ["one","two"]]
moized('one', 'two'); // [["one","two"], ["two","one"]]

NOTE: When combined with onCacheAdd or onCacheHit, this method will always fire last.

onCacheHit

Method to fire when an existing cache item is found. Receives the cache, options, and memoized function as a parameters.

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

const logCacheKeys = (
    cache: Cache,
    options: Options,
    moized: Moized<typeof fn>
) => console.log(cache.keys);

const moized = moize(fn, { maxSize: 2, onCacheHit: logCacheKeys });

moized('one', 'two');
moized('one', 'two'); // [["one","two"]]
moized('two', 'one');
moized('one', 'two'); // [["two","one"], ["one","two"]]

NOTE: When combined with onCacheChange, this method will always fire first.

onExpire

A callback that is called when the cached entry expires.

const fn = (item: string) => item;

const logKey = (key: Key<string>) => console.log(key);

const memoized = moize(fn, { maxAge: 10000, onExpire: logKey });

If you return false from this method, it will prevent the key's removal and refresh the expiration in the same vein as updateExpire based on maxAge:

const fn = (item: string) => item;

let expirationAttempts = 0;

const limitExpirationAttempts = (key: Key<string>) => {
    expirationAttempts += 1;

    return expirationAttempts < 2;
};

const memoized = moize(fn, {
    maxAge: 10000,
    onExpire: limitExpirationAttempts,
});

memoized('one'); // will expire key after 30 seconds, or 3 expiration attempts

NOTE: You must set a maxAge for this option to take effect.

profileName

defaults to function name when it exists, or Anonymous {count} otherwise

Name to use as unique identifier for the function when collecting statistics.

moize.collectStats();

const fn = (item: string) => item;

const memoized = moize(fn, { profileName: 'my fancy identity' });

This is also available via the shortcut method of moize.profile.

const memoized = moize.profile('profile-name')(fn);

NOTE: You must be collecting statistics for this option to provide value, as it is the identifier used for statistics collection.

serializer

defaults to serializeArguments in utils.js

Method used in place of the internal serializer when serializing the parameters for cache key comparison. The function accepts a single argument, the Array of args, and must also return an Array.

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

const customSerializer = (args: string[]) => [JSON.stringify(args[0])];

const memoized = moize(fn, {
    isSerialized: true,
    serializer,
});

This is also available via the shortcut method of moize.serializeWith.

const memoized = moize.serializeWith(customSerializer)(fn);

NOTE: You must set isSerialized for this option to take effect.

transformArgs

Transform the arguments passed before it is used as a key. The function accepts a single argument, the Array of args, and must also return an Array.

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

const ignoreFirstArg = (args: (string | null)[]) => args.slice(1);

const moized = moize(fn, { transformArgs: ignoreFirstArg });

moize('one', 'two', 'three');
moize(null, 'two', 'three'); // pulled from cache

This is also available via the shortcut method of moize.transformArgs.

const memoized = moize.transformArgs(argTransformer)(fn);

If transformArgs is combined with either maxArgs or serialize, the following order is used:

1. limit by maxArgs (if applicable)
2. transform by transformArgs
3. serialize by serializer (if applicable)

updateCacheForKey

If you want to update the cache for a given key instead of leverage the value currently stored in cache.

const fn = (item: string) => item;

let lastUpdate = Date.now();

const memoized = moize(fn, {
    updateCacheForKey([item]: [string]) {
        const now = Date.now();
        const last = lastUpdated;

        lastUpdate = now;

        // its been more than 5 minutes since last update
        return last + 300000 < now;
    },
});

memoized('one');
memoized('one'); // pulled from cache

// 5 minutes later

memoized('one'); // re-calls method and updates cache

This is also available via the shortcut method of moize.updateCacheForKey.

const memoized = moize.updateCacheForKey(shouldCacheUpdate)(fn);

updateExpire

When a maxAge is set, clear the scheduled expiration of the key when that key is retrieved, setting a new expiration based on the most recent retrieval from cache.

const fn = (item: string) => item;

const MAX_AGE = 1000 * 60 * 5; // five minutes

const memoized = moize(fn, { maxAge: MAX_AGE, updateExpire: true });

memoized('one');

setTimeout(() => {
    /**
     * hits cache, which updates the expire to be 5 minutes
     * from this run instead of the first
     */
    memoized('one');
}, 1000 * 60);

Usage with shortcut methods

moize.deep

Pre-applies the isDeepEqual option.

import moize from 'moize';

const fn = (one: string, two: string) => `${one} ${two}`;

export default moize.deep(fn);

moize.infinite

Pre-applies the maxSize option with Infinity.

import moize from 'moize';

const fn = (one: string, two: string) => `${one} ${two}`;

export default moize.infinite(fn);

NOTE: This mimics default behavior of moize prior to version 6.

moize.matchesArg

Pre-applies the matchesArg option as a curriable method.

import moize from 'moize';

const isEqualOrFoo = (cacheKeyArg: string, keyArg: string) =>
    cacheKeyArg === keyArg || keyArg === 'one';

const fn = (one: string, two: string) => `${one} ${two}`;

export default moize.matchesArg(isEqualOrFoo)(fn);

moize.matchesKey

Pre-applies the matchesKey option as a curriable method.

import moize from 'moize';

const fn = (one: string, two: string) => `${one} ${two}`;

const isEqualOrHasFoo = (cacheKey: Key<string>, key: Key<string>) =>
    key.every((keyArg, index) => keyArg === cacheKey[index]) ||
    key.some((keyArg) => keyArg === 'one');

export default moize.matchesKey(isEqualOrHasFoo)(fn);

moize.maxAge

Pre-applies the maxAge option as a curriable method.

import moize from 'moize';

const fn = (one: string, two: string) => `${one} ${two}`;

export default moize.maxAge(5000)(fn);

moize.maxArgs

Pre-applies the maxArgs option as a curriable method.

import moize from 'moize';

const fn = (one: string, two: string) => `${one} ${two}`;

export default moize.maxArgs(1)(fn);

moize.maxSize

Pre-applies the maxSize option as a curriable method.

import moize from 'moize';

const fn = (one: string, two: string) => `${one} ${two}`;

export default moize.maxSize(5)(fn);

moize.profile

Pre-applies the profileName option as a curriable method.

import moize from 'moize';

const fn = (one: string, two: string) => `${one} ${two}`;

export default moize.profile('my fancy identity')(fn);

NOTE: You must be collecting statistics for this option to provide value, as it is the identifier used for statistics collection.

moize.promise

Pre-applies the isPromise and updateExpire options. The updateExpire option does nothing if maxAge is not also applied, but ensures that the expiration begins at the resolution of the promise rather than the instantiation of it.

import moize from 'moize';

const fn = async (one: string, two: Record<string, any>) =>
    await someApiCall(one, two);

export default moize.promise(fn);

NOTE: If you do not want the promise to update its expiration when the cache is hit, then you should use the isPromise option directly instead.

moize.react

Pre-applies the isReact) option for memoizing functional components in React. Key comparisons are based on a shallow equal comparison of both props and legacy context.

import moize from 'moize';

type Props = {
    one: string;
    two: number;
};

const Component = ({ one, two }: Props) => (
    <div>
        {one} {two}
    </div>
);

export default moize.react(Component);

NOTE: This method will not operate with components made via the class instantiation, as they do not offer the same referential transparency.

moize.serialize

Pre-applies the isSerialized option.

import moize from 'moize';

const fn = (one: Record<string, any>, two: Record<string, any>) => ({
    one,
    two,
});

export default moize.serialize(fn);

NOTE: If you want to provide a custom serializer, you should use moize.serializeWith:

moize.serializeWith(customSerializer)(fn);

moize.serializeWith

Pre-applies the isSerialized and serializer options.

import moize from 'moize';

const fn = (one: Record<string, any>, two: Record<string, any>) => ({
    one,
    two,
});

export default moize.serializeWith(JSON.stringify)(fn);

NOTE: If you want to use the default serializer, you should use moize.serialize:

moize.serialize(customSerializer)(fn);

moize.shallow

Pre-applies the isShallowEqual option.

import moize from 'moize';

const fn = (one: string, two: string) => `${one} ${two}`;

export default moize.shallow(fn);

moize.transformArgs

Pre-applies the transformArgs option.

import moize from 'moize';

const fn = ([one, two]: string[]) => [`${one} ${two}`];

export default moize.transformArgs(fn);

moize.updateCacheForKey

Pre-applies the updateCacheForKey option.

import moize from 'moize';

let lastUpdated = Date.now();

const fn = () => {
    const now = Date.now();
    const last = lastUpdated;

    lastUpdate = now;

    // its been more than 5 minutes since last update
    return last + 300000 < now;
};

export default moize.updateCacheForKey(fn);

useMoize hook

If you are using React 16.8+ and are using hooks, you can easily create a custom useMoize hook for your project:

import { useRef } from 'react';

export function useMoize(fn, args, options) {
    const moizedFnRef = useRef(moize(fn, options));

    return moizedFnRef.current(...args);
}

Which can then be used as such:

import React from 'react';

import { useMoize } from './moize-hooks';

function MyComponent({ first, second, object }) {
    // standard usage
    const sum = useMoize((a, b) => a + b, [first, second]);
    // with options
    const deepSum = useMoize((obj) => obj.a + obj.b, [object], {
        isDeepEqual: true,
    });

    return (
        <div>
            Sum of {first} and {second} is {sum}. Sum of {object.a} and{' '}
            {object.b} is {deepSum}.
        </div>
    );
}

Naturally you can tweak as needed for your project (default options, option-specific hooks, etc).

NOTE: This is very similar to useCallback built-in hook, with two main differences:

• There is a third parameter passed (the options passed to moize)
• The second argument array is the list of arguments passed to the memoized function

In both useCallback and useMemo, the array is a list of dependencies which determine whether the funciton is called. These can be different than the arguments, although in general practice they are equivalent. The decision to use them directly was both for this common use-case reasons, but also because the implementation complexity would have increased substantially if not.

Composition

Starting with version 2.3.0, you can compose moize methods. This will create a new memoized method with the original function that shallowly merges the options of the two setups. Example:

import moize from 'moize';

const Component = (props: Record<string, any>) => <div {...props} />;

// memoizing with react, as since 2.0.0
const MemoizedFoo = moize.react(Component);

// creating a separately-memoized method that has maxSize of 5
const LastFiveFoo = moize.maxSize(5)(MemoizedFoo);

You can also create an options-first curriable version of moize if you only pass the options:

import moize from 'moize';

// creates a function that will memoize what is passed
const limitedSerializedMoize = moize({ maxSize: 5, serialize: true });

const getWord = (bird) => `${bird} is the word`;

const moizedGetWord = limitedSerializedMoize(getWord);

You can also combine all of these options with moize.compose to create moize wrappers with pre-defined options.

import moize from 'moize';

// creates a moizer that will have the options of
// {isReact: true, maxAge: 5000, maxSize: 5}
const superLimitedReactMoize = moize.compose(
    moize.react,
    moize.maxSize(5),
    moize.maxAge(5000)
);

Collecting statistics

As-of version 5, you can collect statistics of moize to determine if your cached methods are effective.

import moize from 'moize';

moize.collectStats();

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

const moized = moize(fn);

moized('one', 'two');
moized('one', 'two');

moized.getStats(); // {"calls": 2, "hits": 1, "usage": "50%"}

NOTE: It is recommended not to activate this in production, as it will have a performance decrease.

Stats methods

clearStats

Cear statistics on moized functions.

moize.clearStats(); // clears all stats
moize.clearStats('profile-name'); // clears stats only for 'profile-name'

collectStats

Set whether collecting statistics on moized functions.

moize.collectStats(true); // start collecting stats
moize.collectStats(); // same as passing true
moize.collectStats(false); // stop collecting stats

NOTE: If collecting statistics, it is recommended to provide a custom profileName or use moize.profile() for all memoized functions. This allows easier mapping of resulting statistics to their origin function when it has a common name or is anonymous.

getStats([profileName])

Get the statistics for a specific function, or globally.

moize.collectStats();

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

const moized = moize(fn);

const otherFn = (one: string[]) => one.slice(0, 1);

const otherMoized = moize(otherFn, { profileName: 'otherMoized' });

moized('one', 'two');
moized('one', 'two');

moized.getStats(); // {"calls": 2, "hits": 1, "usage": "50%"}

otherMoized(['three']);

moize.getStats('otherMoized'); // {"calls": 1, "hits": 0, "usage": "0%"}

moize.getStats();
/*
 {
   "calls": 3,
   "hits": 1,
   "profiles": {
     "fn at Object..src/utils.js (http://localhost:3000/app.js:153:68)": {
       "calls": 2,
       "hits": 1,
       "usage": "50%"
     },
     "otherMoized": {
       "calls": 1,
       "hits": 0,
       "usage": "0%"
     }
   },
   "usage": "33.3333%"
 }
 */

Introspection

isCollectingStats

Are statistics being collected on memoization usage.

moize.collectStats(true);
moize.isCollectingStats(); // true
moize.collectStats(false);
moize.isCollectingStats(); // false

isMoized

Is the function passed a moized function.

const fn = () => {};
const moizedFn = moize(fn);

moize.isMoized(fn); // false
moize.isMoized(moizedFn); // true

Direct cache manipulation

The cache is available on the moized function as a property, and while it is not recommended to modify it directly, that option is available for edge cases.

cache

The shape of the cache is as follows:

type Cache = {
    keys: any[][];
    size: number;
    values: any[];
};

Regardless of how the key is transformed, it is always stored as an array (if the value returned is not an array, it is coalesced to one).

NOTE: The order of keys and values should always align, so be aware when manually manipulating the cache that you need to manually keep in sync any changes to those arrays.

cacheSnapshot

The cache is mutated internally for performance reasons, so logging out the cache at a specific step in the workflow may not give you the information you need. As such, to help with debugging you can request the cacheSnapshot, which has the same shape as the cache but is a shallow clone of each property for persistence.

There are also convenience methods provided on the moized function which allow for programmatic manipulation of the cache.

add(key, value)

This will manually add the value at key in cache if key does not already exist. key should be an Array of values, meant to reflect the arguments passed to the method.

// single parameter is straightforward
const memoized = moize((item: string) => item: string);

memoized.add(['one'], 'two');

// pulls from cache
memoized('one');

NOTE: This will only add keys that do not exist in the cache, and will do nothing if the key already exists. If you want to update keys that already exist, use update.

clear()

This will clear all values in the cache, resetting it to an empty state.

const memoized = moize((item: string) => item);

memoized.clear();

get(key)

Returns the value in cache if the key matches, else returns undefined. key should be an Array of values, meant to reflect the arguments passed to the method.

const memoized = moize((one: string, two: string) => [one, two);

memoized('one', 'two');

console.log(memoized.get(['one', 'two'])); // ["one","two"]
console.log(memoized.get(['two', 'three'])); // undefined

getStats()

Returns the statistics for the function.

moize.collectStats();

const memoized = moize((one: string, two: string) => [one, two);

memoized('one', 'two');
memoized('one', 'two');

console.log(memoized.getStats()); // {"calls": 2, "hits": 1, "usage": "50%"}

NOTE: You must be collecting statistics for this to be populated.

has(key)

This will return true if a cache entry exists for the key passed, else will return false. key should be an Array of values, meant to reflect the arguments passed to the method.

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

memoized('one', 'two');

console.log(memoized.has(['one', 'two'])); // true
console.log(memoized.has(['two', 'three'])); // false

keys()

This will return a list of the current keys in cache.

const memoized = moize.maxSize(2)((item: any) => item);

memoized('one');
memoized({ two: 'three' });

const keys = memoized.keys(); // [['one'], [{two: 'three'}]]

remove(key)

This will remove the provided key from cache. key should be an Array of values, meant to reflect the arguments passed to the method.

const memoized = moize((item: { one: string }) => item);

const arg = { one: 'one' };

memoized(arg);

memoized.remove([arg]);

// will re-execute, as it is no longer in cache
memoized(arg);

NOTE: This will only remove keys that exist in the cache, and will do nothing if the key does not exist.

update(key, value)

This will manually update the value at key in cache if key exists. key should be an Array of values, meant to reflect the arguments passed to the method.

// single parameter is straightforward
const memoized = moize((item: string) => item);

memoized.add(['one'], 'two');

// pulls from cache
memoized('one');

NOTE: This will only update keys that exist in the cache, and will do nothing if the key does not exist. If you want to add keys that do not already exist, use add.

values()

This will return a list of the current values in cache.

const memoized = moize.maxSize(2)((item: string | { two: string }) => ({
    item,
}));

memoized('one');
memoized({ two: 'three' });

const values = memoized.values(); // [{item: 'one'}, {item: {two: 'three'}}]

Benchmarks

All values provided are the number of operations per second calculated by the Benchmark suite, where a higher value is better. Each benchmark was performed using the default configuration of the library, with a fibonacci calculation based on a starting parameter of 35, using single and multiple parameters with different object types. The results were averaged to determine overall speed across possible usage.

NOTE: lodash, ramda, and underscore do not support multiple-parameter memoization without use of a resolver function. For consistency in comparison, each use the same resolver that returns the result of JSON.stringify on the arguments.

Filesize

moize is fairly small (~3.86KB when minified and gzipped), however it provides a large number of configuration options to satisfy a number of edge cases. If filesize is a concern, you may consider using micro-memoize. This is the memoization library that powers moize under-the-hood, and will handle most common use cases at 1/4 the size of moize.

Browser support

• Chrome (all versions)
• Firefox (all versions)
• Edge (all versions)
• Opera 15+
• IE 9+
• Safari 6+
• iOS 8+
• Android 4+

Development

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

• benchmark => run the benchmark suite pitting moize against other libraries in common use-cases
• benchmark:alternative => run the benchmark suite for alternative forms of caching
• benchmark:array => run the benchmark suite for memoized methods using single and multiple array parameters
• benchmark:object => run the benchmark suite for memoized methods using single and multiple object parameters
• benchmark:primitive => run the benchmark suite for memoized methods using single and multiple object parameters
• benchmark:react => run the benchmark suite for memoized React components
• build => run rollup to build the distributed files in dist
• clean:dist => run rimraf on the dist folder
• clean:docs => run rimraf on the docs folder
• clean:mjs => run rimraf on the mjs folder
• copy:mjs => run clean:mjs and the es-to-mjs script
• copy:types => copy internal types to be available for consumer
• dev => run webpack dev server to run example app (playground!)
• dist => runs clean:dist and build
• docs => runs clean:docs and builds the docs via jsdoc
• flow => runs flow check on the files in src
• lint => runs ESLint against all files in the src folder
• lint:fix => runs lint, fixing any errors if possible
• test => run jest test functions with NODE_ENV=test
• test:coverage => run test but with code coverage
• test:watch => run test, but with persistent watcher
• typecheck => run tsc against source code to validate TypeScript