Octane Mini Quiz

components.notes\.js

import Component from '@glimmer/component';

export default class Notes extends Component {
  get itemCount() {
    return `(${this.items?.length || 0})`;
  }
}

controllers.application\.js

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

export default class ApplicationController extends Controller {
  @tracked inputValue = '';
  @tracked items = [
  	"Ask about this.",
    "Ask about that."
  ]

  @action
  submit() {
    this.items.push(this.inputValue);
    this.inputValue = '';
  }
}

styles.app\.css

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

h1 { text-align: center; }

ol { 
  background: #FFE;
  border: 1px solid goldenrod;
  margin-bottom: 50px; 
  padding: 15px;
  list-style-position: inside;
  margin: 0 auto 20px;
  max-width: 50%;
}

.note-block {
  background: white;
  border: 1px solid #333;
  border-radius: 4px;
  box-shadow: 0 0 4px rgba(255, 0, 255, 0.2);
  margin: 0 auto;
  padding: 10px;
  max-width: 50%;
}

.note-item-empty {
  color: #999;
  font-style: italic;
}

input { max-width: 100%; }

.note-block hr { margin: 20px 0; }

templates.application\.hbs

<h1>Octane Mini-Quiz</h1>
<ol>
  <li>Why don't the notes in my controller display?</li>
  <li>Why won't the button add a new note to the list?</li>
  <li>Why won't the note count update?</li>
</ol>

<Notes 
  @items={{this.items}} 
  @inputValue={{this.inputValue}}
  @submit={{fn this.submit}} 
/>

templates.components.notes\.hbs

<div class="note-block">
	<h3>My Notes {{this.itemCount}}:</h3>

  <div class="note-items">
    {{#if this.items.length}}
      {{#each this.items as |item|}}
        <div class="note-item">{{item}}</div>
      {{/each}}
    {{else}}
      <div class="note-item note-item-empty">No items.</div>
    {{/if}}
  </div>
   

  <hr />

  <Input @placeholder="Add Item" @value={{@inputValue}} />
  <button {{on "click" @submit}}>Add Note</button>
 </div>

twiddle\.json

{
  "version": "0.17.1",
  "EmberENV": {
    "FEATURES": {},
    "_TEMPLATE_ONLY_GLIMMER_COMPONENTS": true,
    "_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": "1.0.1"
  }
}