New Twiddle

controllers.application\.js

import Controller from '@ember/controller';
import ArrayProxy from '@ember/array/proxy';
import { action } from '@ember/object';

export default class ApplicationController extends Controller {
  appName = 'Ember Twiddle';

  count = 0;

  proxy = ArrayProxy.create({
    content: ['initial', 'content', `revision = ${this.count++}`]
  });

  @action pushObjectProxy() {
    this.proxy.pushObject(`pushed (via proxy) = ${this.count++}`);
  }

  @action pushObjectInner() {
    this.proxy.content.pushObject(`pushed (via inner) = ${this.count++}`);
  }

  @action replaceInnerArray() {
    this.set('proxy.content', ['replaced', 'content', `revision = ${this.count++}`]);
  }

  get innerWithoutSquareBrackets() {
    return '[' + this.get('proxy.content').join(', ') + ']';
  }

  get innerWithSquareBrackets() {
    this.get('proxy.content.[]')
    return '[' + this.get('proxy.content').join(', ') + ']';
  }

  get proxyWithoutSquareBrackets() {
    return '[' + this.get('proxy').toArray().join(', ') + ']';
  }

  get proxyWithSquareBrackets() {
    this.get('proxy.[]')
    return '[' + this.get('proxy').toArray().join(', ') + ']';
  }
}

templates.application\.hbs

<p>
  <code>Inner without .[]</code>:<br>
  <code>{{this.innerWithoutSquareBrackets}}</code>
</p>

<p>
  <code>Inner with .[]</code>:<br>
  <code>{{this.innerWithSquareBrackets}}</code>
</p>

<p>
  <code>Proxy without .content.[]</code>:<br>
  <code>{{this.proxyWithoutSquareBrackets}}</code>
</p>

<p>
  <code>Proxy with .content.[]</code>:<br>
  <code>{{this.proxyWithSquareBrackets}}</code>
</p>



<p>
	<button {{on "click" this.pushObjectProxy}}>
    Push via array proxy
  </button>
</p>

<p>
	<button {{on "click" this.pushObjectInner}}>
    Push via inner array
  </button>
</p>

<p>
	<button {{on "click" this.replaceInnerArray}}>
    Replace inner array
  </button>
</p>

tests.test-helper\.js

import Application from '../app';
import config from '../config/environment';
import { setApplication } from '@ember/test-helpers';
import { assign } from '@ember/polyfills';
import { start } from 'ember-qunit';

let attributes = {
  rootElement: '#test-root',
  autoboot: false
};
attributes = assign(attributes, config.APP);

let application = Application.create(attributes);
setApplication(application);

start();

twiddle\.json

{
  "version": "0.17.1",
  "EmberENV": {
    "FEATURES": {},
    "_TEMPLATE_ONLY_GLIMMER_COMPONENTS": false,
    "_APPLICATION_TEMPLATE_WRAPPER": true,
    "_JQUERY_INTEGRATION": true
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.js",
    "ember": "3.18.1",
    "ember-template-compiler": "3.18.1",
    "ember-testing": "3.18.1"
  },
  "addons": {
    "@glimmer/component": "1.0.0"
  }
}