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-weakmap
import 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