New Twiddle

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  queryParams: ['foo'],
  
  foo: 'bar',
  
  actions: {
    setToNull() {
      this.set('foo', null);
    },
    setToUndefined() {
      this.set('foo', undefined);
    },
    setToFalse() {
      this.set('foo', false);
    },
    setToBar() {
      this.set('foo', 'bar');
    },
    setToBaz() {
      this.set('foo', 'baz');
    }
  }
});

controllers.foo.js

import Ember from 'ember';

export default Ember.Controller.extend({
  queryParams: ['param'],
  param: '',
});

controllers.index.js

import Ember from 'ember';
import { inject as service } from '@ember/service';

export default Ember.Controller.extend({
  router: service(),
  
  actions: {
    transitionWithController() {
      this.transitionToRoute('foo');
    },
    transitionWithRouterService() {
      this.router.transitionTo('foo');
    }
  }
});

router.js

import EmberRouter from '@ember/routing/router';
import config from './config/environment';

const Router = EmberRouter.extend({
  location: 'none',
  rootURL: config.rootURL
});

Router.map(function() {
  this.route('foo');
});

export default Router;

templates.application.hbs

{{outlet}}

templates.foo.hbs

foo route

templates.index.hbs

<button {{action "transitionWithRouterService"}}>transition using router service</button>
<button {{action "transitionWithController"}}>transition using transitionToRoute method of controllery</button>
{{#link-to "foo"}}transition with link-to{{/link-to}}

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"
  }
}