https://github.com/jokeyrhyme/create-internal.js

simple storage and access of private values, powered by WeakMaps
https://github.com/jokeyrhyme/create-internal.js

Last synced: 21 days ago
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simple storage and access of private values, powered by WeakMaps

• Host: GitHub
• URL: https://github.com/jokeyrhyme/create-internal.js
• Owner: jokeyrhyme
• License: mit
• Created: 2016-12-21T04:07:00.000Z (almost 8 years ago)
• Default Branch: master
• Last Pushed: 2020-03-29T05:34:58.000Z (over 4 years ago)
• Last Synced: 2024-10-14T21:23:39.348Z (25 days ago)
• Language: JavaScript
• Size: 1.74 MB
• Stars: 0
• Watchers: 2
• Forks: 0
• Open Issues: 6
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE

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README

        
# create-internal.js [![npm](https://img.shields.io/npm/v/create-internal.svg?maxAge=2592000)](https://www.npmjs.com/package/create-internal) [![Travis CI Status](https://travis-ci.org/jokeyrhyme/create-internal.js.svg?branch=master)](https://travis-ci.org/jokeyrhyme/create-internal.js)

simple storage and access of private values, powered by WeakMaps

## Example

```js

const createInternal = require('create-internal');

// never export `internal`,

// as any code with access to it can access the "private" data within

const internal = createInternal();

class MyClass {

  constructor () {

    Object.assign(internal(this), {

      // accessible to code with this exact `internal` in scope

      privateProperty: 'value'

    });

    Object.assign(this, {

      // accessible to any code that can access the constructed object

      publicProperty: 'value'

    });

  }

  method () {

    const { privateProperty } = internal(this);

    // TODO: do something with privateProperty

  }

}

```

## Usage

We use [`WeakMap`s](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakMap) as the underlying store, which means that any value that is not a [primitive type](https://developer.mozilla.org/en-US/docs/Glossary/Primitive) can be a key, e.g. `Object`, `Array`, `Map`, `Set`, `Function`, etc

### `createInternal()`

returns a function that takes an object and returns a private object associated with it

```js

const createInternal = require('create-internal');

const internal = createInternal(); // never export this

const publicObject = {};

const privateObject = internal(publicObject);

privateObject.privateProperty = 'privateValue';

```

### `createMapInternal()`

returns a function that takes an object and returns a private `Map` associated with it

```js

const { createMapInternal } = require('create-internal');

const internal = createMapInternal(); // never export this

const publicObject = {};

const privateMap = internal(publicObject);

privateMap.set('privateProperty', 'privateValue');

```

## See Also

-   [Mozilla contributor's guide for private properties](https://developer.mozilla.org/en-US/Add-ons/SDK/Guides/Contributor_s_Guide/Private_Properties)

-   [namespace](https://www.npmjs.com/package/namespace)