Share Object Prototypes

components.also-good.js

import Ember from 'ember';

export default Ember.Component.extend({
  myArray: Ember.computed(function() {
    return [];
  }),
  
  init() {
    this._super(...arguments);
    this.get('myArray').push('hello')
  }
});

components.bad-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  myArray: [],
  
  init() {
    this._super(...arguments);
    this.get('myArray').push('hello')
  }
});

components.good-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  myArray: null,
  init() {
    this._super(...arguments);
    this.set('myArray', []);
    this.get('myArray').push('hello');
  }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

templates.application.hbs

<p>
  BAD (all 3 component invocations share same array):

  {{bad-component}}
  {{bad-component}}
  {{bad-component}}
</p>

<p>
  GOOD (arrays are initialized at construction):
  {{good-component}}
  {{good-component}}
  {{good-component}}
</p>

<p>
  Also (arrays are lazily created using computed properties):
  {{also-good}}
  {{also-good}}
  {{also-good}}
</p>

templates.components.also-good.hbs

{{#each myArray as |str|}}
  {{str}}
{{/each}}

templates.components.bad-component.hbs

{{#each myArray as |str|}}
  {{str}}
{{/each}}

templates.components.good-component.hbs

{{#each myArray as |str|}}
  {{str}}
{{/each}}

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.16.2",
    "ember-template-compiler": "2.16.2",
    "ember-testing": "2.16.2"
  },
  "addons": {
    "ember-data": "2.12.1"
  }
}