New Twiddle

controllers.application\.js

import Controller from '@ember/controller';
import { action } from '@ember/object';
import { tracked } from '@glimmer/tracking';

const FRUITS = [
  { name: 'Apple' },
  { name: 'Banana' },
  { name: 'Figs' },
  { name: 'Orange' },
  { name: 'Pear' },
];

export default class ApplicationController extends Controller {
  @tracked name;
  @tracked favoriteFruit;

  fruits = FRUITS;

  @action
  setName(event) {
    this.name = event.target.value;
    
    if (this.name === 'Adelle') {
      this.favoriteFruit = this.fruits.find((fruit) => fruit.name === 'Figs');
    }
  }

  @action
  selectFavoriteFruit(event) {
    let selectedFruitName = event.target.value;
    this.favoriteFruit = this.fruits.find((fruit) => fruit.name === selectedFruitName);
  }
}

templates.application\.hbs

{{#if this.name}}
  <h1>Welcome {{this.name}}!</h1>
  {{#if this.favoriteFruit}}
    <p>I heard you're a fan of {{this.favoriteFruit.name}}.</p>
  {{/if}}
{{/if}}

{{outlet}}

<p>
  Fill in the name with "Adelle" ;)
</p>

<div>
  <label>
    Name
    <input
      type="text"
      value={{this.name}}
      {{on "input" this.setName}}
    />
  </label>
</div>

{{#if this.name}}
  <div>
    <label>
      Favorite fruit
      <select {{on "change" this.selectFavoriteFruit}}>
        <option value="">Select a fruit</option>
        {{#each this.fruits as |fruit|}}
          <option
            selected={{eq this.favoriteFruit.name fruit.name}}
            value={{fruit.name}}
          >
            {{fruit.name}}
          </option>
        {{/each}}
      </select>
    </label>
  </div>
{{/if}}

twiddle\.json

{
  "version": "0.17.1",
  "EmberENV": {
    "FEATURES": {},
    "_TEMPLATE_ONLY_GLIMMER_COMPONENTS": false,
    "_APPLICATION_TEMPLATE_WRAPPER": true,
    "_JQUERY_INTEGRATION": true
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.js",
    "ember": "3.18.1",
    "ember-template-compiler": "3.18.1",
    "ember-testing": "3.18.1"
  },
  "addons": {
    "@glimmer/component": "1.0.0",
    "ember-truth-helpers": "3.0.0"
  }
}