# memoize-immutable

> An efficient memoizer for functions that only receive immutable arguments. Ideal for Redux and similar environments.

Latest version **3.0.0** (published 2016-12-21) · MPL-2.0 license · 0 weekly downloads

## Install

```sh
npm install memoize-immutable
pnpm add memoize-immutable
yarn add memoize-immutable
bun add memoize-immutable
```

## Health

**Score 15/100 (F)** — status: abandoned.

Positive: no vulnerabilities.

Warnings: low downloads; no types; no esm support.

Negative: abandoned; low maintenance score.

## Facts

| | |
|---|---|
| Version | 3.0.0 |
| Published | 2016-12-21 |
| First published | 2016-05-14 |
| Weekly downloads | 0 |
| License | MPL-2.0 |
| TypeScript types | none |
| Module format | CommonJS |
| Node | >=6.6.0 |
| Dependencies | 5 |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 114 |
| Author | @louis_remi |
| Maintainers | louisremi |
| Keywords | immutable, memoize, redux |

## Links

- npm: https://www.npmjs.com/package/memoize-immutable
- Repository: https://github.com/memoize-immutable/memoize-immutable
- Homepage: https://github.com/memoize-immutable/memoize-immutable#readme
- Issues: https://github.com/memoize-immutable/memoize-immutable/issues
- npm.io page: https://npm.io/package/memoize-immutable

## Dependencies (5)

- [lrumap](https://npm.io/package/lrumap.md) ^1.0.0
- [tuplemap](https://npm.io/package/tuplemap.md) ^1.0.2
- [weaktuplemap](https://npm.io/package/weaktuplemap.md) ^1.0.0
- [mixedtuplemap](https://npm.io/package/mixedtuplemap.md) ^1.0.0
- [namedtuplemap](https://npm.io/package/namedtuplemap.md) ^1.0.0

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## Recent versions

- 3.0.0 (latest) — 2016-12-21
- 2.1.0 — 2016-05-20
- 2.0.0 — 2016-05-19
- 1.1.1 — 2016-05-18
- 1.1.0 — 2016-05-17
- 1.0.0 — 2016-05-14

## README

# Memoize Immutable [![npm version](https://badge.fury.io/js/memoize-immutable.svg)](https://badge.fury.io/js/memoize-immutable) [![Build Status](https://travis-ci.org/memoize-immutable/memoize-immutable.svg?branch=master)](https://travis-ci.org/memoize-immutable/memoize-immutable) [![Dependency Status](https://david-dm.org/memoize-immutable/memoize-immutable.svg)](https://david-dm.org/memoize-immutable/memoize-immutable) [![Coverage Status](https://coveralls.io/repos/github/memoize-immutable/memoize-immutable/badge.svg?branch=master)](https://coveralls.io/github/memoize-immutable/memoize-immutable?branch=master)

An efficient memoizer for functions that only receive immutable arguments. Ideal for Redux and similar environments.

This lib is only compatible with browsers that implement `WeakMap` and `Map` natively.
(which have [good browser support](https://kangax.github.io/compat-table/es6/#test-Map)).

## How is it different from other memoizers?

In order to index cached results, most memoizers serialize arguments using `JSON.stringify` or similar methods.
When working with immutable data, using a WeakMap based cache is much more CPU and memory efficient.
This memoizer is designed to work with such caches.

## Install

    npm install --save memoize-immutable

## API

    memoize( fn [, options ] )

- `fn`: the function to memoize
- `options` (optionnal):
  - `cache`: a cache instance implementing `.has`, `.get` and `.set` methods (defaults to TupleMap)
  - `limit`: limit the size of the default cache (incompatible with `cache` option)

`return`s a memoized function.
Note: the `.displayName` of the returned function will be `'<original name>Memoized'`.

## Usage

```javascript
var memoize = require('memoize-immutable');

var nbExecs = 0;
var arraySum = function(arr) {
  nbExecs++;
  return arr.reduce(function(acc, curr) {
    return acc + curr;
  }, 0);
};
var arraySumMemoized = memoize(arraySum);


var arr1 = [ 1, 2, 3, 4, 5, 6 ];
var copy = arr1;

expect(arraySumMemoized(arr1)).to.equal(21);
expect(nbExecs).to.equal(1);

expect(arraySumMemoized(copy)).to.equal(21);
expect(nbExecs).to.equal(1);

// Of course, you shouldn't mutate the arguments, or else...
arr1.push(7);
expect(arraySumMemoized(arr1)).to.equal(21);
expect(nbExecs).to.equal(1);

var clone = arr1.concat();
expect(arraySumMemoized(clone)).to.equal(28);
expect(nbExecs).to.equal(2);
```

## Choosing a cache store

NB: When in doubt, don't use an optional cache.

The following instructions will help choose optimal cache store for a given function. Before you proceed, make sure you know the definition of the following terms:
- *primitive*: Any `number`, `string`, `boolean`, `undefined` or `null` value is considered primitive.
- *non-primitive*: An `object`, `array` or `function` value is non-primitive.
- *named arguments*: here is a function that doesn't accept named arguments:
    `drawRect(20, 50, 100, 150, '#000');`
  and the same function, accepting named arguments:
    `drawRect({x: 20, y: 50, width: 100, height: 150, color: '#000'});`
  which is expected to have the exact same result as:
    `drawRect({color: '#000', width: 100, height: 150, x: 20, y: 50});`

1. The function accepts a single argument (**not named argument**, see below)
  1. The function accepts a single non-primitive argument.
     → use a native WeakMap.
  2. The function accepts a single primitive argument.
     → use the LRUMap (or a native Map if its size isn't a problem).
2. The function accepts multiple arguments, but the number of arguments never changes
  1. The function accepts primitive arguments, **always mixed with at least one non-primitive argument**
     → use the MixedTupleMap.
  2. The function only accepts non-primitive arguments.
     → use the WeakTupleMap.
3. The function accepts a single object of named arguments
  → use the NamedTupleMap.
4. **In any other case**
   → use the default TupleMap.

## license

MPL-2.0

## Author

[@louis_remi](https://twitter.com/louis_remi)

---
_Source: https://npm.io/package/memoize-immutable · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._