New Twiddle

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  isEditing: false,
  init: function () {
    this.data = ['foo'];
  },
  actions: {
  	toggleInput: function () {
      this.toggleProperty('isEditing');
    }
  }
});

templates.application.hbs

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

<ul>
  {{#each data as |d|}}
    <li>{{d}}</li>
  {{/each}}
  <li>
  {{#if isEditing}}
    {{input value=newValue onBlur=(action 'toggleInput')}}
  {{else}}
    <button {{action "toggleInput"}}>Make new</button>
  {{/if}}
  </li>
</ul>

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"
  }
}