optional-path-params

controllers.application.js

import Ember from 'ember';

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

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('filter-noargs', { path: 'filter' });
  this.route('filter', { path: 'filter/*args' });
});

export default Router;

routes.filter-noargs.js

import Ember from 'ember';

export default Ember.Route.extend({
  beforeModel() {
    this._super(...arguments);
    this.replaceWith('filter', ' ');
  }
});

routes.filter.js

import Ember from 'ember';

export default Ember.Route.extend({
  model({ args }) {
    if (args === ' ') {
      alert('no arguments');
    } else {
      const argsArr = args.trim().split('/');
      alert(`args: ${JSON.stringify(argsArr)}`);
    }
  }
});

templates.application.hbs

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

templates.filter-noargs.hbs

<h3>No args</h3>

templates.filter.hbs

<h3>filter</h3>

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"
  }
}