untracked

controllers.application\.js

import Controller from '@ember/controller';

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

	searchParams = new URLSearchParams(window.location.search);
  isViewingChildCid = this.searchParams.has('_cid');
}

templates.application\.hbs

{{#if isViewingChildCid}}
  You got <code>_cid</code> in the URL
{{else}}
  You <strong>not</strong> got <code>_cid</code> in the URL
{{/if}}

twiddle\.json

{
  "version": "0.17.0",
  "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/3.3.1/jquery.js",
    "ember": "3.16.3",
    "ember-template-compiler": "3.16.3",
    "ember-testing": "3.16.3"
  },
  "addons": {
    "@glimmer/component": "1.0.0"
  }
}