Ember.computed.reads

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  foo: null,
  bar: Ember.computed.alias("foo"),
  
  init() {
    this._super(...arguments);
   	
    this.set("foo", "ORIGINAL FOO");
  },
  
  actions: {
    baz() {
      this.set("bar", "SETTING BAR");
    }
  }
});

templates.application.hbs

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

foo:{{foo}}
<br>
bar:{{bar}}
<br>
altBar:{{altBar}}

<button {{action "baz"}}>Action</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"
  }
}