test

components.country-selector\.js

import Component from '@glimmer/component';
import { dropTask, restartableTask } from 'ember-concurrency';
import { tracked } from '@glimmer/tracking';

export default class extends Component {
  @tracked selectedCountry;
  
  countries = [
    "france", 
    "italy",
    "germany",
  ]

	@dropTask *handleSelectCountryTask(country) {
    	this.selectedCountry = country;
    	yield this.args.onSelectCountry(country);
  }
}

controllers.application\.js

import Controller from '@ember/controller';

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

controllers.home\.js

import Controller from '@ember/controller';
import { action } from '@ember/object';
import { tracked } from '@glimmer/tracking';
import { inject as service } from '@ember/service';

export default class HomeController extends Controller {
  @service router;
  @action
  handleSelectCountry(id) {
    console.log(this.router);
    return this.router.transitionTo("success", id)
  }
}

controllers.success\.js

import Controller from '@ember/controller';

export default Controller.extend({
});

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('home', {path: "/"})
  this.route('success', {path: '/success/:id'})
});

export default Router;

routes.home\.js

import Route from '@ember/routing/route';


export default class HomeRoute extends Route {
  async model({ id }) {
    	return id
  }
}

routes.success\.js

import Route from '@ember/routing/route';

const sleep = ms => new Promise(resolve => setTimeout(resolve, ms))

export default class SuccessRoute extends Route {
  async model({ id }) {
    	await sleep(5000);
    	return id
  }
}

templates.application\.hbs

{{outlet}}

templates.components.country-selector\.hbs

<h2>Select your country</h2>
{{#each this.countries as |country|}}
	<button {{on "click" (perform this.handleSelectCountryTask country)}}>
  	{{country}}
    {{if (and (eq this.selectedCountry country) this.handleSelectCountryTask.isRunning) " | LOADING..."}}
  </button>
{{/each}}

templates.home\.hbs

<h1>Homepage</h1>

<CountrySelector @onSelectCountry={{this.handleSelectCountry}} />

templates.success\.hbs

<h1>Success</h1>
You selected {{this.model}}

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",
    "ember-concurrency": "2.2.1",
    "ember-truth-helpers": "3.0.0"
  }
}