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# es6-weak-map
## WeakMap collection as specified in ECMAScript6
_Roughly inspired by Mark Miller's and Kris Kowal's [WeakMap implementation](https://github.com/drses/weak-map)_.
Differences are:
- Assumes compliant ES5 environment (no weird ES3 workarounds or hacks)
- Well modularized CJS style
- Based on one solution.
### Limitations
- Will fail on non extensible objects provided as keys
- While `clear` method is provided, it's not perfectly spec compliant. If some objects were saved as _values_, they need to be removed via `delete`. Otherwise they'll remain infinitely attached to _key_ object (that means, they'll be free for GC only if _key_ object was collected as well).
### Installation
$ npm install es6-weak-map
To port it to Browser or any other (non CJS) environment, use your favorite CJS bundler. No favorite yet? Try: [Browserify](http://browserify.org/), [Webmake](https://github.com/medikoo/modules-webmake) or [Webpack](http://webpack.github.io/)
### Usage
If you want to make sure your environment implements `WeakMap`, do:
```javascript
require('es6-weak-map/implement');
```
If you'd like to use native version when it exists and fallback to polyfill if it doesn't, but without implementing `WeakMap` on global scope, do:
```javascript
var WeakMap = require('es6-weak-map');
```
If you strictly want to use polyfill even if native `WeakMap` exists, do:
```javascript
var WeakMap = require('es6-weak-map/polyfill');
```
#### API
Best is to refer to [specification](http://people.mozilla.org/~jorendorff/es6-draft.html#sec-weakmap-objects). Still if you want quick look, follow example:
```javascript
var WeakMap = require('es6-weak-map');
var map = new WeakMap();
var obj = {};
map.set(obj, 'foo'); // map
map.get(obj); // 'foo'
map.has(obj); // true
map.delete(obj); // true
map.get(obj); // undefined
map.has(obj); // false
map.set(obj, 'bar'); // map
map.clear(); // undefined
map.has(obj); // false
```
## Tests [](https://travis-ci.org/medikoo/es6-weak-map)
$ npm test
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