New Twiddle

controllers.application.js

import Ember from 'ember';
import { computed } from '@ember/object'
import { filter } from '@ember/object/computed'

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  minimum: 1,
  maximum: 100,
  halfway: computed('minimum', 'maximum', {
    get() {
      return Math.round((this.maximum - this.minimum) / 2)
    }
  }),

  items: null,
  
  init() {
    this._super(...arguments)
    
    this.set('items', [{}])
  },

  big: filter('items.@each.val', function(item) { return item.val >= this.halfway}),
  small: filter('items.@each.val', function(item) { return item.val < this.halfway}),

  actions: {
  	addItem() {
  		const val = Math.floor(Math.random() * (this.maximum - this.minimum + 1)) + this.minimum
      this.set('items.firstObject.val', val)
		}
	}
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<p>
	<b>Min:</b> {{minimum}}
  <br>
  <b>Max:</b> {{maximum}}
  <br>
  <b>Halfway:</b> {{halfway}}
</p>

<h3>Items</h3>
<button {{action "addItem"}}>Add Item</button>

<ul>
{{#each items as |item|}}
  <li>{{item.val}}</li>
{{/each}}
</ul>

<h3>Big</h3>
<ul>
{{#each big as |b|}}
  <li>{{b.val}}</li>
{{/each}}
</ul>

<h3>Small</h3>
<ul>
{{#each small as |s|}}
  <li>{{s.val}}</li>
{{/each}}
</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"
  }
}