Dropdown Menu

application.controller.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName:'Dropdown Component',
  
  menuSelectionOptions: [
  	Ember.Object.create({
      label: "Case#: 123",
      value: 1
    }),
    Ember.Object.create({
      label: "Case#: 45699",
      value: 2
    }),
    Ember.Object.create({
      label: "Case#: 789",
      value: 3
    })
  ],
  menuSelection: null,
});

application.template.hbs

<h1>{{appName}}</h1>

<div class="menu-bar">
  {{dropdown-menu items=menuSelectionOptions selection=menuSelection select-item=(action (mut menuSelection))}}
</div>

dropdown-menu.component.js

import Ember from 'ember';

export default Ember.Component.extend({
  
  tagName: 'dropdown-menu',
  classNameBindings: ['hasFocus'],
  attributeBindings: ['tabindex'],
  tabindex: "-1",
  hasFocus: false,
  
  focusIn() {
    this.set('hasFocus', true);
  },
  focusOut() {
    this.set('hasFocus', false);
  },
  mouseEnter() {
    this.set('hasFocus', true);
  },
  mouseLeave() {
    this.set('hasFocus', false);
  },
  
  didInsertElement() {
    this._super();
    this._setScrolling();
  },
  
  _setScrolling() {
    let menu = this.$('.menu_selection-container'),
        menuScrollHeight = menu.prop('scrollHeight'),
        menuHeight = this.get('menuHeight');
    if (menuHeight && menuHeight < menuScrollHeight) {
      menu.css('maxHeight', menuHeight);
      menu.addClass('scrolling');
    }
    else {
      menu.css('maxHeight', '')
      menu.removeClass('scrolling');
    }
  },
    
  actions: {
    selectItem(item) {
      this.sendAction('select-item', item);
      this.set('hasFocus', false);
    }
  }

});

dropdown-menu.template.hbs

<div class="menu_display">
  <div class="menu_selected-item">
    <span class="menu_icon fa fa-caret-down">H</span>
    {{selection.label}}
  </div>
  <span class="menu_caret fa fa-caret-down">H</span>
</div>
<div class="menu_selection-container">
  <ul class="menu_selection-options" role="menu">
    {{#each items as |item|}}
      <li role="menuitemradio">
        <button type="button" {{action "selectItem" item}}>{{item.label}}</button>
      </li>
    {{/each}}
  </ul>
</div>

styles.app.css

body {
  margin: 12px 16px;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 12pt;
}
*, *:before, *:after {
  box-sizing: border-box;
}
.menu-bar {
  height: 40px;
  border-radius: 4px;
  background: linear-gradient(#fff, #eee);
  box-shadow:
    0 0 2px rgba(0, 0, 0, .2),
    0 1px 2px rgba(0, 0, 0, .2);
}

dropdown-menu {
  display: inline-block;
  height: 100%;
  position: relative;
  outline: 0;
  box-shadow: none;
}
dropdown-menu .menu_display {
  height: 100%;
  display: flex;
  position: relative;
  transition: box-shadow 150ms;
}
dropdown-menu .menu_display .menu_caret {
  display: block;
  height: 16px;
  width: 16px;
  line-height: 16px;
  text-align: center;
  position: absolute;
  right: 8px;
  top: calc(50% - 8px);
}
dropdown-menu.has-focus .menu_display {
  height: calc(100% + 1px);
  background-color: #fff;
  border-bottom: 1px dotted rgba(0, 0, 0, 0);
  box-shadow:
    0 0 2px rgba(0, 0, 0, .2),
    0 2px 4px rgba(0, 0, 0, .4);
}
dropdown-menu .menu_selected-item {
  margin: auto 0;
  position: relative;
}
dropdown-menu .menu_display .menu_selected-item .menu_icon {
  display: block;
  height: 16px;
  width: 16px;
  line-height: 16px;
  text-align: center;
  position: absolute;
  left: -20px;
  top: calc(50% - 8px);
}
dropdown-menu .menu_selection-container {
  background-color: #fff;
  overflow-y: hidden;
  height: 0;
  outline: 0;
  position: relative;
  transition: 150ms;
}
dropdown-menu .menu_selection-container.scrolling {
  overflow-y: scroll;
}
dropdown-menu.has-focus .menu_selection-container {
  height: auto;
  box-shadow:
    0 0 2px rgba(0, 0, 0, .2),
    0 2px 4px rgba(0, 0, 0, .4);
}
dropdown-menu .menu_selection-options {
  margin: 0;
  padding: 0;
  list-style: none;
}
dropdown-menu .menu_display,
dropdown-menu .menu_selection-options button {
  padding: 8px 32px 8px 28px;
}
dropdown-menu .menu_selection-options button {
  font-size: inherit;
  display: block;
  width: 100%;
  text-align: left;
  background: none;
  border: 0;
  outline: 0;
}
dropdown-menu .menu_selection-options button:hover,
dropdown-menu .menu_selection-options button:focus {
  background-color: rgba(0, 0, 0, .02);
}
dropdown-menu .menu_selection-options button.active {
  background-color: rgba(0, 0, 0, .6);
  color: #eee;
}

twiddle.json

{
  "version": "0.4.16",
  "EmberENV": {
    "FEATURES": {}
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.1.0/ember.debug.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.1.0/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.1.0/ember-template-compiler.js"
  }
}