New Twiddle

helpers.$\.js

import { helper } from '@ember/component/helper';

export default helper(function $([selector]) {
  return document.querySelector(selector);
});

templates.application\.hbs

<h1>What's in your <code>&lt;head&gt;</code> right now?</h1>

<pre><code>
{{#let ($ "head") as |head|}}
  {{head.innerHTML}}
{{/let}}
</code></pre>

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": "3.17.0",
    "ember-template-compiler": "3.17.0",
    "ember-testing": "3.17.0"
  },
  "addons": {
    "@glimmer/component": "1.0.0"
  }
}