dynamic page layout

controllers.application.js

import Ember from 'ember';

const {set, get, computed} = Ember;

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  selectedGroupId: 0,
  
  groups: [
    {label: 'first', items: ['text', 'checkbox']},
    {label: 'second', items: ['select', 'textarea']}
  ],
  
  selectedGroup: computed('selectedGroupId', function() {
    return this.groups[this.selectedGroupId];
  }),
  
  actions: {
    changeGroup: function(e) {
      set(this, 'selectedGroupId', e.target.value);
    }
  }
});

helpers.eq.js

import Ember from 'ember';

export function eq(params/*, hash*/) {
  return params[0] === params[1];
}

export default Ember.Helper.helper(eq);

styles.app.css

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

textarea, label {
  display: block;
}

fieldset  {
  margin: 5px 0px;
}

templates.application.hbs

<style>
</style>
<h1>Welcome to {{appName}}</h1>
<label>
  Fieldset selector: 
  <select onchange={{action "changeGroup"}}>
  {{#each groups as |group num|}}
    <option value="{{num}}">{{group.label}}</option>
  {{/each}}
  </select>
</label>

<fieldset>
{{#each selectedGroup.items as |item|}}
  {{#if (eq item "text")}}
    <label>
      {{item}}: <input value="{{item}}"/>
    </label>
  {{/if}}
  {{#if (eq item "checkbox")}}
    <label>
      <input type="checkbox" /> {{item}}
    </label>
  {{/if}}
  {{#if (eq item "select")}}
    <label>
      {{item}}: 
      <select><option>{{item}}</option></select>
    </label>
  {{/if}}
  {{#if (eq item "textarea")}}
    <label>
      {{item}}: 
      <textarea>{{item}}</textarea>
    </label>
  {{/if}}
{{/each}}  
</fieldset>
<br>
<br>
{{outlet}}
<br>
<br>

twiddle.json

{
  "version": "0.8.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.5.1",
    "ember-data": "2.5.2",
    "ember-template-compiler": "2.5.1"
  }
}