# instance-memoize

> [![Greenkeeper badge](https://badges.greenkeeper.io/akito0107/instance-memoize.svg)](https://greenkeeper.io/)

Latest version **1.0.0** (published 2018-06-24) · apache-2.0 license · 0 weekly downloads

## Install

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

## 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 | 1.0.0 |
| Published | 2018-06-24 |
| First published | 2018-03-03 |
| Weekly downloads | 0 |
| License | apache-2.0 |
| TypeScript types | none |
| Module format | CommonJS |
| Dependencies | 1 |
| Unpacked size | 244.9 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 0 |
| Author | Akito Ito |
| Maintainers | akito_ito |

## Links

- npm: https://www.npmjs.com/package/instance-memoize
- Repository: https://github.com/akito0107/instance-memoize
- Homepage: https://github.com/akito0107/instance-memoize#readme
- Issues: https://github.com/akito0107/instance-memoize/issues
- npm.io page: https://npm.io/package/instance-memoize

## Dependencies (1)

- [object-hash](https://npm.io/package/object-hash.md) ^1.3.0

## Recent versions

- 1.0.0 (latest) — 2018-06-24
- 0.1.1 — 2018-03-03
- 0.1.0 — 2018-03-03

## README

# instance-memoize

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[![Test Coverage](https://api.codeclimate.com/v1/badges/93020a6dd00c043f4593/test_coverage)](https://codeclimate.com/github/akito0107/instance-memoize/test_coverage)

flexible cache wrapper for js object.

## Getting Started

### Prerequisites
- Node.js v8+
- npm or yarn

### Installing

```
$ npm add instance-memoize
```

## Usage

### basic example
`instance-memoize` cached results of method invocation on the specified object *permanently*.
If you want to manage cache purging and lifetime see [custom cache example](#with custom cache).

```js
import memoize from 'instance-memoize'; // or const memoize = require('instance-memoize') for commonjs modules

const obj = {
  calledCounter: 0,
  method: function() {
    calledCounter++;
    return "test value";
  }
};

const wrapped = memoize({
  instance: obj,
  methods: ['method']
})

console.log(wrapped.method())      // output => "test value"
console.log(wrapped.calledCounter) // output => "1"

/*
  The result of "method" is stored internal cache,
  From the second call, the result is returned via cache.
 */
console.log(wrapped.method())      // output(from cache) => "test value"  
console.log(wrapped.calledCounter) // output => "1"
```

### with es2015 classes
```js
import memoize from 'instance-memoize'; // or const memoize = require('instance-memoize') for commonjs modules

class Sample {
  constructor() {
    this.calledCounter = 0;
  }
  someMethod() {
    this.calledCounter++;
    return "value";
  }
}

const wrapped = memoize({
  instance: new Sample(),
  methods: ['someMethod']
})

console.log(wrapped.someMethod())      // output => "test value"
console.log(wrapped.calledCounter)     // output => "1"

console.log(wrapped.someMethod())      // output(from cache) => "test value"  
console.log(wrapped.calledCounter)     // output => "1"
```

### with async functions
`instance-memoize` also works with async/await or Promise. 

```js
import memoize from 'instance-memoize'; // or const memoize = require('instance-memoize') for commonjs modules

class Sample {
  constructor() {
    this.calledCounter = 0;
  }
  async someMethod() {
    this.calledCounter++;
    return "value";
  }
}

const wrapped = memoize({
  instance: new Sample(),
  methods: ['someMethod']
})

console.log(await wrapped.someMethod())   // output => "test value"
console.log(wrapped.calledCounter)        // output => "1"

console.log(await wrapped.someMethod())   // output(from cache) => "test value"  
console.log(wrapped.calledCounter)        // output => "1"
```

### with custom cache
You can use your customized cache by passing cache instance via options.
`cache` instance must implement three methods;
- get(key: string) :Object
- set(key: string, obj: any)
- reset()

This example shows `instance-memoize` working with [isaacs's node-lru-cache](https://github.com/isaacs/node-lru-cache).
```js
import memoize from 'instance-memoize'; // or const memoize = require('instance-memoize') for commonjs modules
import LRU from 'lru-cache' // import isaacs's node-lru-cache

class Sample {
  constructor() {
    this.calledCounter = 0;
  }
  someMethod() {
    this.calledCounter++;
    return "value";
  }
}

const wrapped = memoize({
  instance: new Sample(),
  methods: ['someMethod'],
  options: {
    cache: LRU({ ...lruCacheOptions })
  }
})
```

## API

### `memoize(instance, [...methodNames], options)`
#### arguments
- instance (Object): Source object that wrapped to.
- methodNames (Array<string>): Method name(s) that cached.
- options (Object):
    - cache (Object): Custom Cache object
    - keygen (function(methodName: string, ...args): string ): cache key generator function

#### returns
(Object): Wrapped instance that caches the result of specified method invocation.

## Authors
* **Akito Ito** - *Initial work* - [akito0107](https://github.com/akito0107)

## License

This project is licensed under the Apache2.0 License - see the [LICENSE.md](LICENSE.md) file for details

---
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