Application Loading Substate

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

routes.application.js

import Ember from 'ember';
import { Promise } from 'rsvp';

export default Ember.Route.extend({
	model() {
    // This is like doing `return this.store.findAll('post');`, imitating a request latency with the setTimeout.  
		return new Promise((resolve) => {
			setTimeout(resolve, 5000);
		});
  }
});

routes.index.js

import Ember from 'ember';

export default Ember.Route.extend({
  	model() {
    // This is like doing `return this.store.findAll('post');`, imitating a request latency with the setTimeout.  
		return new Promise((resolve) => {
			setTimeout(resolve, 5000);
		});
  }
});

templates.application-loading.hbs

<h2>APPLICATION LOADING... SUBSTATE</h2>

templates.application.hbs

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

templates.loading.hbs

<h2>LOADING...</h2>

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": "3.1.4",
    "ember-template-compiler": "3.1.4",
    "ember-testing": "3.1.4"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}