simple-list-select

components.my-list.js

import Ember from 'ember';

export default Ember.Component.extend({
  tagName: 'ul',
  classNames: 'list-options',
  selectedOption: null,
    
  init() {
  	this._super(...arguments);
    this.set('options', [
      { id: 1,
        name:'item 1'
      },
      { id: 2,
        name:'item 2'
      },
      { id: 3,
        name:'item 3'
      },
      { id: 4,
        name:'item 4'
      },
    ]);
  },
  
  actions: {
  	onSelect(option) {      
    	this.set('selectedOption', option);
    }
  }
});

components.my-list.my-item.js

import Ember from 'ember';
import { computed } from '@ember/object';
export default Ember.Component.extend({
 	tagName: 'li',
  classNames: 'list-option',
  classNameBindings: ['isSelected:selected'],
  
  isSelected: computed('selectedOption.id', function() {
		return this.get('selectedOption.id') === this.get('option.id');
  }),
});

controllers.application.js

import Ember from 'ember';

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

styles.app.css

body {
  margin: 12px 16px;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 12pt;
}

.list-options {
	list-style-type: none;
  padding: 0;
  margin: 0;
	border: 1px solid #e5e5e5;
  cursor: default;
  padding: 0 0 .5em;
  box-sizing: border-box;
  overflow: auto;
  max-height: 18em;
  box-shadow: 0 0 0.5rem 0 rgba(0,0,0,.25);
  font-size: .9375rem;
  line-height: 1.34;
  border-radius: .25rem;
}

.list-options:hover {
	border-color: #555;
}

.list-option {
	display: flex;
  justify-content: space-between;
	padding: .375rem 1.25rem;
  font-size: .875rem;
  color: #4a90e2;
  cursor: pointer;
}

.list-option.selected {
  background-color: #4a90e2;
  color: #fff;
}

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{my-list}}
<br>
<br>

templates.components.my-list.hbs

{{#each options as |option|}}
	{{my-list/my-item
  	option=(readonly option)
    selectedOption=(readonly selectedOption)
    onSelect=(action "onSelect")
  }}
{{/each}}

templates.components.my-list.my-item.hbs

<span onClick={{action onSelect option}}>{{option.name}}</span>
{{#if isSelected}}<span>&check;</span>{{/if}} 

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"
  }
}