localstorage

controllers.application.js

import Ember from 'ember';
import { storageFor } from 'ember-local-storage';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  favorites: storageFor('favorites'),
  
  init() {
    this._super();
    window.f = this.get('favorites');
  }
});

storages.favorites.js

import StorageObject from 'ember-local-storage/local/object';

export default StorageObject.extend({
  addFavorite(id) {
    this.set('favorites', this.get('favorites').pushObject(id));
  },
  
  removeFavorite(id) {
    this.set('favorites', this.get('favorites').removeObject(id));
  },
  
  favorites: Ember.computed({
    get() {
      const id = this.get('catalogContext.guid');
      let favorites = this.get(id);
      if (!favorites) {
        favorites = Ember.A();
        this.set(id, favorites);
      }
      return favorites;
    },
      
    set(key, value) {
      this.set(this.get('catalogContext.id'), value);
      return value;
    }
  })
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>

twiddle.json

{
  "version": "0.10.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.6.0",
    "ember-data": "2.6.1",
    "ember-template-compiler": "2.6.0"
  },
  "addons": {
  	"ember-local-storage": "*"
  }
}