Check Boxes

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  testArray: [
    Ember.Object.create({name: 'first', isChecked: true}),
    Ember.Object.create({name: 'second', isChecked: true}),
    Ember.Object.create({name: 'third', isChecked: true}),
    Ember.Object.create({name: 'fourth', isChecked: true})
  ],
  
  actions: {
   toggleChecked() {
    var testArray = this.get('testArray');
    var i;
   	for (i=0; i < testArray.length; i++) {
     if (testArray[i].isChecked) {
      	testArray[i].set('isChecked', false);
      } else {
       	 testArray[i].set('isChecked', true);
      }
    }
   } 
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>
{{#each testArray as |testItem|}}
<input type="checkbox" checked={{if testItem.isChecked 'checked'}} />
{{/each}}

<br>
<br>

<button {{action 'toggleChecked' ''}}>Toggle Checked</button>

twiddle.json

{
  "version": "0.15.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.2.2",
    "ember-template-compiler": "3.2.2",
    "ember-testing": "3.2.2"
  },
  "addons": {
    "ember-data": "3.2.0"
  }
}