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   1 # es6-weak-map
   2 ## WeakMap collection as specified in ECMAScript6
   3
   4 _Roughly inspired by Mark Miller's and Kris Kowal's [WeakMap implementation](https://github.com/drses/weak-map)_.
   5
   6 Differences are:
   7 - Assumes compliant ES5 environment (no weird ES3 workarounds or hacks)
   8 - Well modularized CJS style
   9 - Based on one solution.
  10
  11 ### Limitations
  12
  13 - Will fail on non extensible objects provided as keys
  14 - 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).
  15
  16 ### Installation
  17
  18         $ npm install es6-weak-map
  19
  20 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/)
  21
  22 ### Usage
  23
  24 If you want to make sure your environment implements `WeakMap`, do:
  25
  26 ```javascript
  27 require('es6-weak-map/implement');
  28 ```
  29
  30 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:
  31
  32 ```javascript
  33 var WeakMap = require('es6-weak-map');
  34 ```
  35
  36 If you strictly want to use polyfill even if native `WeakMap` exists, do:
  37
  38 ```javascript
  39 var WeakMap = require('es6-weak-map/polyfill');
  40 ```
  41
  42 #### API
  43
  44 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:
  45
  46 ```javascript
  47 var WeakMap = require('es6-weak-map');
  48
  49 var map = new WeakMap();
  50 var obj = {};
  51
  52 map.set(obj, 'foo'); // map
  53 map.get(obj);        // 'foo'
  54 map.has(obj);        // true
  55 map.delete(obj);     // true
  56 map.get(obj);        // undefined
  57 map.has(obj);        // false
  58 map.set(obj, 'bar'); // map
  59 map.clear();         // undefined
  60 map.has(obj);        // false
  61 ```
  62
  63 ## Tests [![Build Status](https://travis-ci.org/medikoo/es6-weak-map.png)](https://travis-ci.org/medikoo/es6-weak-map)
  64
  65         $ npm test