Inspect

controllers.application\.js

import Controller from '@ember/controller';
import { tracked } from '@glimmer/tracking';
import { guidFor } from '@ember/object/internals';

function inspect(target, key, descriptor) {
  const { initializer } = descriptor;
  descriptor.initializer = function $inspectInit() {
    const value = initializer.call(this);
    console.log(`[initialized] ${this.constructor.name}<${guidFor(this)}>.${key}`, value);
   return value;
  };
  const desc = tracked(target, key, descriptor);
  const { set } = desc;

  desc.set = function $inspectSet(value) {
    set.call(this, value);
    console.log(`[update] ${this.constructor.name}<${guidFor(this)}>.${key}`, value);
  };

  return desc;
}

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

  constructor() {
    super(...arguments);
    setTimeout(() => { this.appName = 'Ember Fiddle';}, 0);
    setTimeout(() => {
      this.appName = 'Glimmer Fiddle';
    }, 3000);
    setTimeout(() => {
      this.appName = 'Glimmer Twiddle';
    }, 6000);
  }
}

templates.application\.hbs

<h1>Welcome to {{this.appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>

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"
  }
}