This addon is a polyfill for the Ember.WeakMap RFC.
A WeakMap provides a mechanism for storing and retrieving private state. The WeakMap itself does not retain a reference to the state, allowing the state to be reclaimed when the key is reclaimed.
A traditional WeakMap (and the one that will be part of the ES2015 language) allows for weakness from key -> map, and also from map -> key. This allows either the Map, or the key being reclaimed to also release the state.
Unfortunately, this bi-directional weakness is problematic to polyfill. Luckily, uni-directional weakness, in either direction, "just works". A polyfill must just choose a direction.
Note: Just like ES2015 WeakMap, only non null Objects can be used as keys
ember install ember-weakmapimport Ember from 'ember'; const myWeakMap = new Ember.WeakMap();/* * @method set * @param key {Object} * @param value {Any} * @return {Any} stored value */ const emailObj = { id: 1, subject: 'Hello World' }; myWeakMap.set(emailObj, {read: true});The key must be an object.
/* * @method get * @param key {Object} * @return {*} stored value */ myWeakMap.get(emailObj); // => { read: true } myWeakMap.get(someObjThatWasNotSet); // => undefined/* * @method has * @param key {Object} * @return {Boolean} if the key exists */ myWeakMap.has(emailObj); // => true myWeakMap.has(someObjThatWasNotSet); // => false/* * @method delete * @param key {Object} */ myWeakMap.delete(emailObj); myWeakMap.get(emailObj); // => undefined myWeakMap.has(emailObj); // false