Squares

components.nifty-squares\.hbs

<h2>Nifty Squares</h2>

<label for="toggle">Show squares?</label>
<Input id="toggle" @type="checkbox" name="isAdmin" @checked={{this.this.showSquares}} />

<div class="nifty-squares">
  {{#if this.showSquares}}
    {{yield}}
  {{/if}}
</div>

components.nifty-squares\.js

import Component from '@glimmer/component';
import { tracked } from '@glimmer/tracking';
import { customElement } from 'ember-custom-elements';

@customElement('nifty-squares')
export default class NiftySquaresComponent extends Component {
  @tracked
  showSquares = true;
}

controllers.application\.js

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

const COLORS = ['red', 'orange', 'yellow', 'green', 'blue', 'violet'];

function generateSquares() {
  return Array(16).fill().map(() => {
    const color = COLORS[Math.floor(Math.random() * Math.floor(COLORS.length + 1))];
    return {
      style: htmlSafe(`background-color: ${color};`),
      visible: !!Math.floor(Math.random() * Math.floor(2))
    };
  });
}

export default class ApplicationController extends Controller {
  @tracked
  squares;

  init() {
    super.init(...arguments);
    this.refreshSquares();
  }

  @action
  refreshSquares() {
    this.squares = generateSquares();
    later(this.refreshSquares, 200);
  }
}

styles.app\.css

nifty-squares {
  --square-size: 50px;
}

.nifty-squares {
  display: flex;
  flex-shrink: 0;
  flex-wrap: wrap;
  margin-top: 50px;
  width: calc(var(--square-size) * 4);
}

.squares-parent {
  display: contents;
}

.square {
  flex-shrink: 0;
  height: var(--square-size);
  width: var(--square-size);
}

.square-color {
  height: 100%;
  width: 100%;
}

templates.application\.hbs

<nifty-squares>
  <!-- A non-dynamic parent element is required
       for any dynamic content passed, otherwise
       the renderer will encounter problems -->
	<div class="squares-parent">
    {{#each this.squares as |square|}}
      <div class="square">
        {{#if square.visible}}
          <div class="square-color" style={{square.style}}></div>
        {{/if}}
      </div>
    {{/each}}
  </div>
</nifty-squares>

twiddle\.json

{
  "version": "0.17.1",
  "ENV": {
    "emberCustomElements": {
      "deoptimizeModuleEval": true
    }
  },
  "EmberENV": {
    "FEATURES": {},
    "_TEMPLATE_ONLY_GLIMMER_COMPONENTS": false,
    "_APPLICATION_TEMPLATE_WRAPPER": true,
    "_JQUERY_INTEGRATION": false
  },
  "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-custom-elements": "2.0.1"
  }
}