New Twiddle

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  veryLongString: Ember.computed(function() {
    let str = '';
    for (let i = 0; i < 10; i++) {
      for (let ch = 65; ch < 65+26; ch++) {
        str += String.fromCharCode(ch);
      }
    }
    str = str.replace('Z', '@');
    return str;
  })
});

helpers.break-word.js

import Ember from 'ember';

export function breakWord(params/*, hash*/) {
  let word = params[0];
  return Ember.String.htmlSafe(word.replace('@', '@​'));
}

export default Ember.Helper.helper(breakWord);

styles.app.css

body {
  margin: 12px 16px;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 12pt;
}
.break-wrapper {
  outline: 2px solid red;
  max-width: 400px;
  overflow-x: scroll;
  margin: 2em;
  padding: 2em;
}

templates.application.hbs

<h1>Demo of using the zero-width space entity to break a string</h1>
<br>
<p>First box below does not use the zero-width space, 2nd box does, after the first '@'</p>
<br>
<div class="break-wrapper">
{{veryLongString}}
</div>
<div class="break-wrapper">
{{break-word veryLongString}}
</div>
<br>
<br>

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"
  }
}