ember-int-htmlattr-delay

controllers.application\.js

import Controller from '@ember/controller';
import {action} from '@ember/object';
import { inject as service } from '@ember/service';

export default class ApplicationController extends Controller {
  appName = 'Ember Twiddle';
	@service intl;

	date = new Date();

  constructor(...args) {
    super(...args);
    this.intl.on('localeChanged', () => {
      if (this.intl.locale.includes('fr')) {
        for (let i=0; i<10000; i++)
          console.log('slow');
      }
    });
  }

	@action
	testMe() {
    console.log('action', [this.intl.locale.includes('fr') ? 'fr' : 'en']);
    this.intl.setLocale([this.intl.locale.includes('fr') ? 'en' : 'fr']);
  }
}

styles.app\.css

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

div.date
 {
  //background: blue;
  display: inline-block;
}

[lang=fr] div.date {
  background: red;
}

templates.application\.hbs

<h1>Welcome to {{this.appName}}</h1>
<br>
<br>
<div>
<div class="date">
{{format-date date}}
</div>
</div>
<button {{on 'click' this.testMe}}>Testme</button>
{{outlet}}
<br>
<br>

twiddle\.json

{
  "version": "0.17.0",
  "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/3.3.1/jquery.js",
    "ember": "3.17.0",
    "ember-template-compiler": "3.17.0",
    "ember-testing": "3.17.0"
  },
  "addons": {
    "@glimmer/component": "1.0.0",
    "ember-intl": "4.3.1"
  }
}