object freeze sorting

controllers.application.js

import Ember from 'ember';
import { alias, gt, sort } from '@ember/object/computed';


export default Ember.Controller.extend({
  appName: 'Ember Twiddle',

  letters: [
    { name: 'b' },
    { name: 'c' },
    { name: 'a', value: 1 },
    { name: 'a', value: 3 },
    { name: 'a', value: 2 }
  ],
  
  lettersSorting: Object.freeze(['name']),
  sortedLetters: sort('letters', 'lettersSorting'),
  
  actions: {
    toggleSort() {
      if (this.lettersSorting.lastObject === 'value') {
        this.lettersSorting.popObject();
      } else {
        this.lettersSorting.pushObject('value');
      }
    }
  }

});

templates.application.hbs

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

{{#each sortedLetters as |letter|}}
  <p>{{letter.name}} - {{letter.value}}</p>
{{/each}}

<button {{action 'toggleSort'}}>
  Toggle sort
</button>

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}