mastery rendering

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

helpers.color-block.js

import Ember from 'ember';

export function colorBlock([percentage, color]) {
  
 // return "<div style='width: 100%; height: ${percentage}%'>${percentage}</div>";
  return Ember.String.htmlSafe(`<div style='width: 100%; height: ${percentage}%; background-color: ${color}'></div>`);

}

export default Ember.Helper.helper(colorBlock);

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<div style="width: 100px; height: 100px; border-radius: 5px;">  
   <div style="background-color: darkgreen; width:100%; height: 10%"></div>
   <div style="background-color: green; width:100%; height: 20%"></div>
   <div style="background-color: palegreen; width:100%; height: 50%"></div>
   <div style="background-color: lightgray; width:100%; height: 20%"></div>
</div>


<div style="width: 100px; height: 100px; border-radius: 5px;">  
   {{color-block 10 'pink'}}
   {{color-block 20 'crimson'}}
   {{color-block 30 'purple'}}
</div>

<br>
<br>

twiddle.json

{
  "version": "0.7.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "1.13.13",
    "ember-data": "1.13.15",
    "ember-template-compiler": "1.13.13"
  }
}