details component

components.x-details.js

import Ember from 'ember';

export default Ember.Component.extend({
  tagName: 'details',
  attributeBindings: ['open'],
  open: true,
  click(e) {
		e.preventDefault();
  },
  actions: {
    toggle() {
      this.toggleProperty('open', false);
    }
  }
});

controllers.application.js

import Ember from 'ember';

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

templates.application.hbs

{{x-details}}

templates.components.x-details.hbs

<summary {{action 'toggle'}}>Details</summary>
<ul>
  	<li {{action 'toggle'}}>click to close</li>
    <li>one</li>
    <li>one</li>
    <li>one</li>
    <li>one</li>
  </ul>

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"
  }
}