Middle Truncate

controllers.application.js

import Ember from 'ember';

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

helpers.truncate.js

import Ember from 'ember';

const {
  isPresent
} = Ember;

export function truncate([ value = '', length = 10 ], { separator = '...' }) {
  if (!isPresent(value) || value.length <= length) {
    return value;
  }
  
	const charsToShow = length - separator.length;
  const frontChars = Math.ceil(charsToShow / 2);
  const backChars = Math.floor(charsToShow / 2);
  
  return `${value.substr(0, frontChars)}${separator}${value.substr(value.length - backChars)}`;
}

export default Ember.Helper.helper(truncate);

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>

{{truncate 'Please Haters Back Off: Season 2' 20}}

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.12.0",
    "ember-template-compiler": "2.12.0",
    "ember-testing": "2.12.0"
  },
  "addons": {
    "ember-data": "2.12.1"
  }
}