dynamic route

controllers.application\.js

import Controller from '@ember/controller';

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

controllers.test\.js

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

export default class TestController extends Controller {
  @service router;
  
  @action
  go() {
    this.router.transitionTo('/test/yay/stuff');
	}
};

router\.js

import EmberRouter from '@ember/routing/router';

export default class Router extends EmberRouter {
  location = 'none';
}

Router.map(function () {
  this.route('test', {path: '/test/:parent/:child'});
  this.route('test', {path: '/test/:parent'});
	this.route('test');
});

routes.test\.js

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

export default class TestRoute extends Route {
  
  model({ parent, child }) {
   	return { parent, child } 
  }
  
 
};

templates.application\.hbs

<h1>Welcome to {{this.appName}}</h1>
<LinkTo @route="test">Here</LinkTo>
<br>
<br>
{{outlet}}
<br>
<br>

templates.test\.hbs

<div>
	parent: {{@model.parent}}
</div>
<div>
	child: {{@model.child}}
</div>

<button role="button" {{on "click" this.go}}>Go</button>

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-data": "3.18.0"
  }
}