New Twiddle

components.my-component.js

import Ember from 'ember';
import { inject as service } from '@ember/service';

export default Ember.Component.extend({
  progressBar: service(),
  didInsertElement() {
    this._super(...arguments);
    
  }
});

controllers.application.js

import Ember from 'ember';
import { inject as service } from '@ember/service';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  progressBar: service(),
  actions: {
    showProgress() {
      this.get('progressBar').startLoading();
    },
    endProgress() {
      this.get('progressBar').endLoading();
    }
  }
});

services.progress-bar.js

import Ember from 'ember';
import { later } from '@ember/runloop';

export default Ember.Service.extend({
   start() {
     let interval = (1000/60); // 16fps
      let ratio = .1;
      let progress = 0;

      let timer = setInterval(() => {
        progress = progress + ((progress || 20) * ratio);
        if (ratio < 0.0005) {
          ratio = ratio * .999;
        } else {
          ratio = ratio * .97;
        }

        this.set('width', `${progress}%`);
        if (progress > 100) {
          this.set('width', `100%`);
          clearInterval(timer);
        }
      }, interval);
     
     this.timer = timer;
   },
    startLoading() {
      this.set('width', 0);
      this.set('canShow', true);
      this.start();
    },
    endLoading() {
      clearInterval(this.timer);

      this.set('width', `100%`);
      this.set('complete', true);

      later(() => {
        this.set('width', 0);
        this.set('complete', false);
        this.set('canShow', false);
      }, 300);
    }
});

styles.app.css

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

.progress-complete {
	transition: width linear .15s;
}

.progress {
  position: absolute;
  height: 3px;
	background: #0eb477;
  top: 0;
  left: 0;
}

.progress-lead {
  position: absolute;
  right: 0;
  top: 0;
  height: 100%;
  width: 40px;
  box-shadow: #0eb477ff 0px 0px 10px;
  transform: rotate(3deg) translate(0px,-4px);
  translate: -10%;
}

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{my-component}}
<button {{action "showProgress"}}>heel</button>
<button {{action "endProgress"}}>stop</button>
{{outlet}}
<br>
<br>

templates.components.my-component.hbs

{{# if progressBar.canShow}}
  <div class="progress {{if progressBar.complete 'progress-complete'}}" style="width:{{progressBar.width}}">
    <div class="progress-lead"></div>
  </div>
 {{/if}}

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"
  }
}