push unshift array

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  init() {
    this._super(...arguments);
   	this.set('items', Em.A(['111', '222', '333'])); 
  },
  
  actions: {
    appendItem() {
      this.get('items').pushObject('new');
    },
    insertItem() {
      this.get('items').unshiftObject('new');
    }
  }
});

controllers.application.js

import Ember from 'ember';

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

templates.application.hbs

{{my-component}}

templates.components.my-component.hbs

Items: {{items}}

<ul>
	{{#each items as |item|}}
    <li>{{item}}</li>
  {{/each}}
</ul>

<button onclick={{action 'insertItem'}}>Insert Item</button>
<button onclick={{action 'appendItem'}}>Append Item</button>

twiddle.json

{
  "version": "0.13.0",
  "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": "2.16.3"
  }
}