Non-shared arrays

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({

  init() {
    this._super(...arguments);
    this.set('myArr', Ember.A([]));
  },

  actions: {
    addNumber() {
      let random = Math.ceil(10 * Math.random());
      this.get('myArr').pushObject(random);
    }
  }
});

controllers.application.js

import Ember from 'ember';

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

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<h2>My fist component</h2>
{{my-component}}
<h2>My second component</h2>
{{my-component}}
<br>
<br>

templates.components.my-component.hbs

<ul>
{{#each myArr as |num|}}
  <li>{{num}}</li>
{{/each}}
</ul>

<button {{action "addNumber"}}>
  Add number
</button>

twiddle.json

{
  "version": "0.9.3",
  "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"
  }
}