New Twiddle

controllers.application.js

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

export default Ember.Controller.extend({
  router: service(),
  appName: 'Ember Twiddle',
  value: 0,
  
  queryParams: ['value', 'value2'],
  
  isActive0: computed('router.currentURL', function() {
    return this.router.isActive('index', { queryParams: {
      value: 0
    } });
  }),
  isActive1: computed('router.currentURL', function() {
    return this.router.isActive('index', { queryParams: {
      value: 1
    } });
  }),
  isActive2: computed('router.currentURL', function() {
    return this.router.isActive('index', { queryParams: {
      value: 2
    } });
  }),
});

styles.app.css

body {
  margin: 12px 16px;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 12pt;
}

button {
  font-size: 1.2rem;
}

button.active {
  background: blue;
  color: white;
}

templates.application.hbs

<h1>Click on a Button To See if Active</h1>

<p>Value = {{value}}</p>

<p>
	<button onclick={{action (mut value) 0}} class="{{if isActive0 'active'}}">Pick = 0</button>
	<button onclick={{action (mut value) 1}} class="{{if isActive1 'active'}}">Pick = 1</button>
  <button onclick={{action (mut value) 2}} class="{{if isActive2 'active'}}">Pick = 2</button>
</p>

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"
  }
}