currentURL Issue

controllers.application.js

import Ember from 'ember';

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

controllers.login.js

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

export default Ember.Controller.extend({
  router: service(),
  
  actions: {
    login() {
      this.get('router').transitionTo('success');
    }
  }
});

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('login');
  this.route('success');
});

export default Router;

routes.login.js

import Ember from 'ember';

export default Ember.Route.extend({
});

routes.success.js

import Ember from 'ember';

export default Ember.Route.extend({
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
{{#link-to "login"}}Login{{/link-to}}
<br>
<br>
{{outlet}}
<br>
<br>

templates.login.hbs

<h2>Login</h2>
<form {{action "login"}}>
	<button type="submit">Submit</button>
</form>

templates.success.hbs

<h2>Success!</h2>

twiddle.json

{
  "version": "0.15.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.2.2",
    "ember-template-compiler": "3.2.2",
    "ember-testing": "3.2.2"
  },
  "addons": {
    "ember-data": "3.2.0"
  }
}