Declaratively selecting an option from a list

components.size-chooser-list.js

import Ember from 'ember';

export default Ember.Component.extend({
  actions: {
    onSelect(sizeValue) {
      this.get('onSelectSize')(sizeValue);
    }
  }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',

  selectedSize: '1gb',

  sizeOptions: [
    {
      value: '1gb',
      label: '1 GB'
    },
    {
      value: '2gb',
      label: '2 GB'
    },
    {
      value: '4gb',
      label: '4 GB'
    },
    {
      value: '8gb',
      label: '8 GB'
    },
    {
      value: '16gb',
      label: '16 GB'
    },
  ],

  actions: {
    onSelectSize(sizeValue) {
      this.set('selectedSize', sizeValue);
    }
  }
});

helpers.eq.js

// Stolen from https://emberigniter.com/how-to-equals-conditional-comparison-handlebars/
// to avoid the ember-truth-helpers dependency

import Ember from 'ember';

const eq = (params) => params[0] === params[1];
export default Ember.Helper.helper(eq);

styles.app.css

body {
  margin: 12px 16px;
  font-family: sans-serif;
}

.size-chooser-list-item {
  cursor: pointer;
}

templates.application.hbs

<h1>Choose a size</h1>
{{size-chooser-list
  selected=selectedSize
  options=sizeOptions
  onSelectSize=(action "onSelectSize")
}}

templates.components.size-chooser-list.hbs

<ul>
  {{#each options as |size|}}
    <li 
      {{action "onSelect" size.value}}
      class="size-chooser-list-item {{if (eq selected size.value) "selected"}}">
      {{size.label}}
      {{#if (eq selected size.value)}}
        <span style="color: red;">selected</span>
      {{/if}}
    </li>
  {{/each}}
</ul>

twiddle.json

{
  "version": "0.13.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.16.2",
    "ember-template-compiler": "2.16.2",
    "ember-testing": "2.16.2"
  },
  "addons": {
    "ember-data": "2.16.3"
  }
}