Ember accordion

components.accordion-component.js

import Ember from 'ember';

export default Ember.Component.extend({
	tagName: '',
});

components.accordion-item.js

import Ember from 'ember';

export default Ember.Component.extend({
  activeItem: {},
  
  title: '',
  isOpen: false,
  
  tagName: '',
  
  didInsertElement() {
  	this._super(...arguments);
    if (this.get('isOpen')) {
    	this.set('activeItem.id', this.get('tabId'));
    }
  },
  
  isCollapsed: Ember.computed('tabId', 'activeItem.id', function() {
    return this.get('tabId') === this.get('activeItem.id');
  }),

  tabId: Ember.computed(function() {
  	return Math.trunc(Math.random() * 10000);
  }),
  
  actions: {
    toggle() {
      this.set('activeItem.id', this.get('isCollapsed') ? undefined : this.get('tabId'));
    },
  },
});

controllers.application.js

import Ember from 'ember';

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

styles.app.css

* {
  line-height: 1;
  padding: 0;
	margin: 0;
}

body {
  font-family: sans-serif;
}

[role="tab"] {
	background-color: #eee;
  border-bottom: 1px solid #fff;
  font-weight: normal;
	padding: 0.5em 1em;
}

[role="tab"]:focus {
	background-color: #ddd;
  outline: 0;
}


[role="tabpanel"] {
	padding: 1em; 
  border-bottom: 1px solid #eee;
}

templates.application.hbs

{{#accordion-component}}
	{{#accordion-item title='Header'}}
  	content
  {{/accordion-item}}
  {{#accordion-item isOpen=true title='Header'}}
  	content
  {{/accordion-item}}
  {{#accordion-item title='Header'}}
  	content
  {{/accordion-item}}
{{/accordion-component}}

templates.components.accordion-component.hbs

<div role='tablist'>
	{{yield}}
</div>

templates.components.accordion-item.hbs

<h3
  aria-expanded={{if isOpen "true" "false"}}
  aria-controls="tabpanel-{{tabId}}"
  id="tab-{{tabId}}"
	tabindex="0"
  role="tab"
  onclick={{action "toggle"}}
>
	{{title}}
</h3>

{{#liquid-if isCollapsed}}
	<div
    aria-hidden={{if isOpen "false" "true"}}
    aria-labelledby="tab-{{tabId}}"
    id="tabpanel-{{tabId}}"
    role="tabpanel"
  >
		{{yield}}
  </div>
{{/liquid-if}}

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.12.0",
    "ember-template-compiler": "2.12.0",
    "ember-testing": "2.12.0"
  },
  "addons": {
    "liquid-fire": "0.27.3"
  }
}